That is still a odd score of years out of Gauntlet. But not at all unlikely.
Not at all, very plausible. I stand corrected.
What about the other points, though?
-Ben.
Oh well a Tytalus with a low Parma score? Thats like a pacifist Flambeau. 
And with a Puissant or an Affinity or something this should be easy... or with many adventure exp pumped into Parma or with an extrmly high form specialization.
And the other points... I think Area Lores and many other skills are for companions, many skills can be taught with 30 exp per season and a combat mage or a nature mage or a lab rat mage wont need things like Intrigue or Artes Liberales very much.
Is 30 xp for a skilled teacher in a teaching focused lab one on one? How do you get 30 xp per season?
What is that thing you're talking about? In-trigue? flips through Ignem summa No, I don't have the faintest clue. flips through Latin-Flambeau dictionary Ahhhhhh. "Intrigue: see Pilum of Fire volume 7."
+3 Com +5 Teaching +2 Puissant +12 single student +5 good teacher virtue +3 teaching room = 30 exp... ok this IS a very good and expensive teacher which isnt very easy to find... but not the LEDENDARY teacher with Com +5 and teaching 10(12)... which would give you 37 exp the absolute maximum.
Ok not the maximum g if the student have an affinity and the apt student virtue it would be 60 exp per season 
As you pointed out, someone with Good Teacher, +3 Com and Puissant Teaching already isn't your run-of-the-mill teacher, you know. It's a darn good teacher, who can probably command a job in just about any University. If a player created one such, I'd give him a stern look, for it's obviously a min-maxing attempt.
Oh, and you can add a "single student" specialty, and Mythic Communication (teaching) for an extra two points. 
Which other skills to you leave to the companions? Avoiding Professions or Crafts I can understand for non-Verditius, but so many others are important to interaction at Tribunal-- bargaining when you need to talk about preliminary issue resolution, folk ken and guile when arguing at Tribunal, intrigue and leadership to marshal votes... certainly some of these can be roleplayed, but with no basis in a skill, I'd think you'd want to be fantastic at them in real life before taking a stab at it in a Tribunal. And events at Tribunal can certainly shape then next seven years of any one of those magus types-- access to contested Vis sources, claims of deprivation, simple policy declarations can all put a serious kink in the long-term plans.
Artes Liberales drives the alphabets you can read... What about texts in Coptic, Welsh, Greek, Arabic, and Hebrew? Or does every book arrive in Latin for your saga? For us, it's fairly important...its addition to ritual casting is a pleasant side effect.
And I would argue that you don't want to be travelling a locaton without a modicum of area lore...or if Wizards' War rolls around, regardless of which side you're on, wouldn't it be a good thing to know where the hiding places are? Standing stones? Old battlefields? You might have a high Magic Realm Lore and know about griffons or basilisks, but knowing where in the region these things would nest isn't something your average companion hunter or knight or merchant would know.
It's a case of YSMV, I guess. 
-Ben.
+12 single student?
I read the bonus as +6 from page 164. I see that there is an unspecified +3 bonus in the calculation on this page that you have not included above, I don't understand where the other +3 comes from.
The player may actually have the concept of "Good Teacher". 
They should probably have a Story Hook
as to why they are not teaching in the great universites ,
or being sought out by nobles and suchlike.
Other players/npcs benefit from the Teaching , the Teacher himself does not.
I suspect such characters are just there to be an XP pump rather than be played, at which point you'd really be better off just paying for a specialist during covenant creation.
Courted by X - Minor Story Flaw: the (specialist) character is actively courted by an agency external to the covenant (university, noble household, etc) who would very much appreciate acquiring his services for themselves. If the character doesn't respond to their overtures, they may begin a sabotage campaign to make his life at the covenant miserable and their offer more attractive in comparison. The character gains an appropriate good reputation at level 2.
Now it's up to the covenant to work to keep their great teacher. 
I can only speak of my saga:
a) the Bonisagus is a lab-rat who cant speak (but can cast spells without words or gestures) and have the blatant gift... so he uses a magical device to speak to the mind of his owl companion (which can turn into human form) and the owl companion have high skill scores (and some magical powers that push his authority) ok his Mt score is aout 10 a15 years out of gauntlet and his Profession Scribe and Latin scores hit the 5 but other things... now but that fits the character cery well.
b) the Tytalus is a master of Intrigue, Folk Ken, has something in leadership, is already a Master, he can use Ledgerdemain and such skill, he is also good at Hermetic Law and in Organisation Lore: order of Hermes and in fearie Lore... but he also have a Parma Magica of 5 and Creo and Auram scores of around 20. Its very nice to see him using his Intrigue skill always push the other player chars to things they dont want to do.
c) the ex Miscellanea who is a necromancer has a very high Leadership skill in order to command his undeads. Lately the players discovered a city of the ancients and he plans to re-develope the language of the old one. In order to do this he just learned greek and arabic and he plans to summon an old egypt scribe so he can learn old egypt including the hieroglyphes. And for his he has a Artes Lieberales Score of 6... and as an old diabolist (ok his master was this 
) he also have Infernal Lore very high. Oh and he is a studied medic.
d) the Verditius is the lazy boy of the covenant, he pushes his scores in the arts, in MT, in his craft skill, in Artes Liberales and Philosophia but in every social thing he is not useful at all... in fact he often drives the Tytalus mad because he ruins all of the percet plots of him. And his free time he uses to eat and sleep... ^^
The Companions are also adding their knowledge to the group... the one his very good at socializing, sneeking, gambling ect, the other one (zhe half-giant) is THE wise man having high scors in nearly every Lore, Academic skill or such thing, escpecially in church skills (he will obtain his first true fait point soon) and the others also have good skills.
Area Lore... I realize that nobody skills it... but why should they? They have their trub capitain who was in nearly every part of eurpe or their rangers or merchants or a normal grogs who was grown up in the place they want to. In one of teh last sessions they traveled to Scandinavia and they didnt have anyone in their covenant with knowledge abput this... so they went to Lübeck and asked Oculus Sepentrionalis if they would lend them some good men.
And yes: every hermetic book (or book writen by a hermetic magus about any subject) IS in latin... and nearly every academic book is in latin or greek, only subjects like Area Lores, Craft, Intrigue or such things are writen in "normal" language. Latin IS the language of knowledge.
@Tyrell: yeah only +9 for a single student.
Our saga is now 20 years out of gautlet, while our mages don't seem to have the raw power of many of the ones discussed here, they are certainly rather menancing. Our prolific spellcraft Bjornaer has a lab total up in the 60's, more with experimentation but this is the highest in the covenant. Our necromancer has the highest arts but nothing above 15 (a couple at 14 odd). Skills are generally quite high although this is mainly due to the saga starting in 4th ed. Hence parma and magic theory tend to be very high (parma is about 9 for our Bjornaer, magic theory about 11). Arts in general are low. Magic items few and far between but those that there are, are often powerful (teleport charms, powerful talismans, etc).
We have just added some freshly gauntleted mages to the covenant and a few of us plan to take these young magi out with one or two of the older ones every now and then. The original trio of gantlet +20 mages represent the kind of threat now that can only be countered by really big nasty stuff. Their only weak area really is in fighting things with high parma and so far preference seems to be to either change into heartbeast form (a bear for the bjornaer) or get crazy with mundane (but very sharp knives), our flambeau has a brawling skill around 6ish. very nasty.
I have to admit a lot of the skill values quoted seem very high to me. Skill 5 or 6 represents a very large amount of skill points and it is dubious in the extreme that every adventure would realistically allow you to put skill points in those skills. Being trained in them is only possible if there is a teacher with a skill higher than yours so how would you develop your parma to that level except through either practice or experience and neither of these should allow so rapid a progression.
If mages 20 years out of guantlet are so danagerous my feeling is you are: allowing too much training, giving too much xp in adventures, giving too many books with too high a quality rating and giving too much lab time.
Lets be frank it takes a LOT of time to move around mythic europe. You can spend months to just get to the place you are going and months getting back. We were over a year on a single adventure one time so that was a lot of time away from the books and not a lot of xp to show for it comparitively.
I can speak from experience of the Covenent project for 4th edition that even a single season every two years devoted to non-hermetic things, coupled with a season of adventure and a season devoted to the covenent can slow down character progression to avoid a lot of this überness. The flaw that requires you to spend a season a year doing other things is actually a MAJOR not minor flaw when you look at its real game effect.
I was under the impression that a lot of what is being discussed here was supposed to have been "dealt with" in 5th edition. Especially things like played apprentices being better than created by the rules ones. I know that building 3 apprentices in the covenent project resulted in far better starting mages that the rules allowed but without them being über. The 4th edition rules gave too little skill points (particularily in magic theory which should have been about twice what the rules gave), about the right amount of art points and too many spell points (or you have to assume that the apprentice is a mirror of the master). And that was without going overboard on the apprentice in terms of time of instruction or resources given to them. Teaching an apprentice was another major time sink by the way.
So if you are finding your mages too strong then I think that you need to look at what you are doing in detail and see what you can do to halt the spiral...or not if you aren't upset by the situation.
I'm not an SG myself, but it does seem like these players have had it too easy. But if you, and they are happy with it, then there is no problem 
If you really want to do something about it - they incur the wrath of a powerful fey lord.
His curse is that it is harder for them to retain knowledge. Every year they must spend time re-reading books or using their current knowledge and spells. If they neglect an art or a skill, it decreases over time.
This effect increases slightly every 3rd year
(basically lose 1 exp for every 3 years of age until the curse is lifted)
That's a risky thing to run. I would not personally choose to do it, ever.
Players tend to like keeping what their characters have "earned". In my experience taking away a character's xp makes for unhappy players, and unhappy players make for a wretched game.
Adding a powerful npc to the story just to tone down the characters may serve to weaken the story, makeing it seem more artifical (It certainly would in my present game). Yet even if the story accomodates the new element comfortably, I would suggest that a different curse could be just as effective at powering down the players, or even significantly more effective, without upsetting the players nearly as much.
Must agree with Erik on this.
As a player i would be extremely unhappy about such a curse.
If you think that you may have been too generous as the SG ,
later encounters can make up for it.
A few times i make encounters "apparently" easier than the players would expect.
This is to encourage them to investigate.
If they don't worry about it , then difficulties increase , as they are unprepared.
Parma's always there for XP expenditure on adventures...very few magi are going to go out and about without it. But as I said, the big parma score we have in our game came from 4E experience. Most parmas of 5E aren't much above 3 yet.
On a side note, do you consider the adventure experience quality guideline to be for an entire arc, or for a session?
We tend to see very small xp awards per session-- 1 to 3, with a larger award of maybe 5 xp at the end of the arc... with an arc often lasting a season or more over three to six sessions. An important or monmental arc might last full game year or more. Two magi who took a trip into the Mediterranean from the Stonehenge Tribunal got a few texts and some non-hermetic magical items that still need to be investigated, some enemies, some very interesting encounters, but lost more than a couple of grogs, a right arm, and a lot of lab time, such that the Tremere was told explicitly by the Exarch, "Get thee to the Laboratory." I don't know if the trip was really worth they could have done in the lab
You can sometimes turn the covenant-devoted season to a magus' advantage, researching some item or spell that extends one's own knowledge while providing a benefit. It's not a sure thing, but it's worth trying to do. Wounds and healing can really slow down a magus, too.
I have to really agree with this point. My magus just got his first apprentice, and unfortunately, the ranking Bonisagus in the tribunal is also an enemy of the covenant. She's already made it clear that if she ever feels that the instruction being provided is substandard, she'll claim the apprentice. That means that when my magus isn't teaching or learning teaching in order to compensate for his less-than-stellar communication, he's doing his season of work for the covenant or paying for teaching from the Redcap companion who has a decent score... I think my magus has perhaps three free seasons coming in the next three years and they're occupied with a longevity ritual, a leap of homecoming text and the Gathering of 12 Years. While those will give my magus some exposure or adventure experience, he's not going to see his arts rise much further for a number of years. Later on, he'll probably have to learn a wad of spells he might not otherwise, to attempt to give his apprentice some better options. In the meantime, he'll gain a teaching score of about four, maybe five by the end of the apprenticeship, but only with a serious investment of seasons being taught Teaching and paying for that tutoring.
The apprentice, though, should show up as a decent generalist. I think being forced to ensure the education is quality will end up giving the equivalent of the skilled parens, arcane lore, and clan ilfetu virtues. Not bad, but then having one's hand forced by covenant enemies is a little frustrating. In all the projections I've done, you end up much better playing out a magus through apprenticeship than just designing one out of Gauntlet. The important difference, IMO, is that playing out the apprenticeship means your character has the potential to be put in harm's way and possibly killed over the course of one's education. That's a fair exchange, as far as I'm concerned.
The same magi who went into the Mediterranean also lost three years inside a regio. That didn't help their studies much, either... but it's a way to hold the magi at a certain point as the world around them advances. I wouldn't want it happen more than once or twice...it would certainly increase the precautions taken when approaching such a place.
Just some ideas,
-Ben.