We're getting to the end of this. It won't go on forever. I've removed the statements where I didn't have anything new to add.
With apprentices available (especially young ones) the mentor charges others for the creation of te AC's. To paraphrase you in a way that emphasizes the value of apprentices, AC's are useful for a,b,c, and d but in general only type d gets made because the cost of a season is too high for magi. Apprentices can be used to tap in to this pent up demand and produce AC's at a lower cost. (which if you might think is still too high) but in all of the situations where ACs are actually created and some of the ones where they aren't an apprentice can provide value to their mentor by doing the work for their mentor. An apprentice created AC is a saved season for someone else that's a pretty good value.
Obviously you send the apprentice to the lab when you're in the library and o the library to copy texts when you are in the lab. The vis supply being self correcting in a game because there are stories that you want to play and they can't all be about gathering vis is a way to look at it. Another way to look at it is that vim vis is more or less the most useful substance in the entire world for magi and if it doesn't have value in your game you're doing something really weird with resources. Also NPC covenants and PC covenants are necessarily different. Every starship in the federation can't possibly see as much weird stuff as the Enterprise protagonists are different. The factors that drive the value for apprentices in the order as a whole may be different than what you see in a game.
If one uses the RoP:M rules, vis extraction is not something you want to do unless you are very, very desperate. You also don't want to do anything that might cause you to roll dice even on the "good" table.
I think I did not manage to get my point through.
ACs are useful for a,b and c. But these are situation in which fixed ACs are only very, very, very marginally more useful than "plain" but judiciously picked ACs that require virtually no time investment by a magus. Roughly speaking, that's because in cases a,b, and c a magus has many opportunities to "renew" the ACs. Instead of fixing an AC to each of your grogs, just pick a new lock of hair now and then. Because of this, I've almost never seen magi who'd be willing to spend seasons to fix those ACs even if they could get three ACs fixed for each season of effort (i.e. spend a season teaching your apprentice, and the apprentice then spends three seasons fixing ACs).
Case d is different because you often can't be that picky about which AC you pick from a (relatively powerful) enemy, and you can't renew it easily - getting some AC is hard enough to do, even once. But most magi don't make that many enemies in their lifetimes, particularly personal enemies (enemies of the entire covenant see the burden of fixing the respective ACs shared). From my experience, even a meddling covenant will not see more than 2 or 3 enemies per magus per century, and most will see less than that. Incidentally, these fixing jobs are exactly the type of jobs that you do not want to delegate, or take from someone else, because it's dangerous stuff. "Hey amicus, yes, our covenant had a lot of trouble with that prince of Hell, the Slayer of Nations. But last year we managed to confront it and gouge out one of its eyes, a potent Arcane Connection with which we can now keep it in check. But, you know, these things expire so ... that young girl you took as an apprentice last year, her Arts should be open by now, right? Since we are all far too busy to deal with fixing Arcane Connections, would you mind having her give a quick fix to the eye of the Slayer of Nations for us?"
Again, I probably failed to express my thoughts clearly enough.
What I meant is this. If I look at published material, from the prices of books in pawns of vis, to the amount of vis that published covenants collect, to the ease of finding vis with a "vis hunt" (the rules in tCatC) or by striking appropriate deals with faeries etc. etc. I get the impression that most established magi (those who can teach an apprentice) will prize one of their own seasons at least as much as the amount of Vim vis that an apprentice can extract in three seasons (and this disregards the effort/risk/inconvenience of finding the apprentice, sharing a lab or setting up a new one etc.). This is also what I've seen in virtually every saga I played in, though in this second regard my perceptions might be skewed because sagas tend to self-adjust: if vis is scarce troupes will tell interesting stories that will increase its availability.
Uhm, this may be derailing the original question a bit but I can't refrain from asking ... why?
Sure, you do not want to perform a lot of vis extraction without pouring vis back into the environment, but what harm is there in a few (say 2 or 3) "magus seasons" per year?
And why is rolling dice even on the Aura strengthening table so bad? Sure, a botch can be bad (but you can roll 0 botch dice). The only other results that are mildly bad, and they are bad essentially for the covenfolk alone, not the magi, are 10 (the occasional random spontaneous effect that gives 1 warping point to anyone subject to it - but anyone protected by a Parma should be immune) and 13 (here and there the Aura increases, and mundane residents get 1 Warping point).
It's been a while since I read that chapter. IIRC, it is remarkably easy to trigger a roll on one table or the other. IIRC, it is remarkably easy to need one or more botch dice on the 'good' table, and that even some of the 'good' results are very bad, such as taking a normal high aura and turning that into a regio, most of which isn't as good, aside from all the problems of suddenly having a regio create.
(BTW, five events that generate Warping Points give all covenfolk a Minor Flaw all at once. Yay, story of the Cursed Covenant, if covenfolk behave vaguely like real people rather than resources.)
From a meta perspective, the rules cause weird things to happen surprisingly often, and add die rolls to downtime, which ought to not require them, and maybe story events. These rules drive covenants toward specific Hooks, like it or not. These rules make large covenants utterly impractical, because magical activity scales with the number of magi. Just, ugh.
The main problem with those rules isn't the scaling with number of magi, but the linear nature of the rules. It's as easy to raise a Magic Aura of 1 to Magic Aura of 2 as it is to raise a Magic Aura of 8 to a Magic Aura of 9.
Why the Ars Magica bog standard pyramid cost rules (probably using the pyramid cost of Abilities, not Arts) weren't used for this sort of thing puzzles me to this day.
Magic Creature: Welcome to the Magic Realm, new friends! Since you have just severed your home's physical connection to the mundane world, I expect we will have a lot of time to get to know each other.
Magi: Well, crap.
Back to the subject of magical schools, I have long been of the opinion that a lecture circuit or a centralized school makes good sense for education of apprentices.
If the magi are only interested in having lab helpers, it's more efficient to have one mage (possibly a Redcap) teach magic theory to a class of two to twenty than have n magi individually teach magic theory. If the magi want their filii to have the many abilities/lores a mage needs, a teacher is again more efficient.
A tuition of one pawn of vis x students saves a season for the magi masters and provides a vis income for the teaching mage; alternately, a debt-of-service system trades needs for needs. You can't lecture Arts, but Arts are not the only thing a mage needs. I might argue the Arts are the least important need for an apprentice, given access to a good library as a young mage.
Your ungifted teacher got -3 to teaching total for each gifted student. So the best maximized teacher will give to the students the same experience earned in a season of exposure as assistance. Gifted teachers must suffers the students fighting each others, the competence and the unfriendship. Only a teacher with high Parma can teach many students per season. Maybe an archimagus with the motivation will do it. Or in a context of low vis maybe he can do it for 2/3 p each season. With Parma 8 he can earn 16/24 p x season, supposed more than her Cr Vi lab total allow. Anyway is better to contract an ungifted teacher for only your apprentice to teach Latin and artes liberales and let the discipulus to read the canon of magic theory before to take him inside your lab as assistant.Cheaper and faster.
I have been under the impression that the penalty did not stack, and an unaffected teacher especially didn't have to worry about this kind of feedback loop nonsense. Otherwise the -3 penalty would compound for every mundane student who was affected by the gift and became more disruptive as well.
Learned Magicians have it easier: A charm or charta cast on the classroom to provide everyone with the minor virtue to not be offended by the Gift. Charm redone daily; charta redone daily or monthly. If they're willing to deal with Warping, they can also add Good Teacher, Good Student, Increased Characteristics (Com) or Essential Nature (com +3 or +6 for teaching) and Puissant Teaching to the mix. Or they can use Transformed Being to ignore the Warping.
Far from having problems in a university setting, LMs thrive there, which may be why that's where they are found. Nothing prevents magi from enrolling Hermetic apprentices in such a class, except for the problems that will occur outside the classroom. Gruagachan might also be useful for granting virtues for a while, but the nature of these spells automatically builds in stories as the geas is challenged.
This was one of the unresolved issues (I think) that came out of the last time we had this discussion - if it stacks with itself on the entire group, then yes, the scenario is completely unworkable. If it doesn't then it's "merely" incredibly difficult to manage.
The other issue is the in-game RP elements of the effect of the Gift - it's an environment of inherent distrust. No one in their right mind would want to work in such an environment, even if they intellectually knew that all the children they were teaching weren't actually serial killers out to eat their livers. Similarly, such a scenario is crazy-insane stressful for the children, who don't have the mental maturity to learn in such an environment.
Thus the necessity for the "unaffected by the gift" minor virtue.
Alternately, you MAYBE could get around this with a sort of holo-projection, whereby none of the children were actually in the room with each other (essentially two-way Rego Imagium at Arcane range); however, as someone pointed out last time, that starts to get a bit too clever with attempting to get around the Gift, which is something that is usually more difficult to do than one thinks.
Yeah, I think the other option was Figurine magic, but that takes a season of work for 1 figurine (I think), that only lasts for...2 seasons? Not what you might call "efficient".
I've not seen any example of the Gift stacking, or of the Parma needing to be high to shield the negative impression of the Gifted. This interpretation would make Tribunals difficult or impossible.
A Gifted mage teacher does make sense, as opposed to an unGifted Redcap.
This brings up the question, again, of how Redcaps operate effectively with magi in general.
I do find it odd that hermetic magic cannot temporarily create virtues; not social status ones, ones that alter experience or grant abilities. Just ones like Lesser Immunity or Unaffected by the Gift. I was completely fine with it, until I picked up Hedge Magic Revised and saw hedge wizards doing so easily and violating the common sense limitations I would have placed on it.
That is a rather large flaw in Hermetic Magic Theory.
Not exactly a flaw; Hermetic Magic does a lot of the same stuff in a different way: Where LMs can temporarily raise characteristics with virtues, magi can do it permanently; where LMs grant Puissant Charm, magi can grant bigger bonuses, typically +3, along the lines of using Im to have a good voice, or just go straight for ReMe and avoid the roll altogether. Even treated well, even with Parma, a LM is usually no match for a magus. Not even close. An unnerfed LM might be more of a Rival Magic than a Hedge Magic; if SuFo didn't need to Penetrate, LMs would be almost as good as magi
BTW, Gruagachan can also grant virtues, but not to themselves.
Magi have difficulty with a lot of things that are easy for other traditions.