Consider that up to 10 days off in a season don't reduce your Lab Total. So you could be out and about, enjoying a pint at the local tavern, and meanwhile, when in the lab, you take a few days to research a spell that would heat the ale of a man who offended you at the pub, and next time you go to the pub, you can have his pint of ale be warm when he goes to drink it. And if you have Deft Ignem, or enough Mastery, or Casting total, you can do it with no gestures, or words.
except in medieval times, unless it is winter or the publican has a large store of ice in the cellar, the beer is going to be warm anyway (room temperature).
So perhaps a spell of boiling beer or refrigerated beer?
EDIT sorry to be knee-jrerk pedantic, and detract from the thread.
Obviously the cold beer example was figurative, not literal.
The advantages of knowing rather than sponting low level spells don't just include penetration. They are also much more resistant to adverse casting conditions.
I have a Magus whose main arts are Creo and Ignem. We started a chapter house for Oculus, and our Library isn't great. We have some great Summaes, but it's not comprehensive, and we have quite a few Arts we have no Summa in.
So, in order to improve them, namely Animal and Perdo, my character has been researching low level spells.
This allows him to increase his score, and to have some spells that he can reliably cast, like a touch range PeIg spell to inflict Fatigue.
Low magnitude spells can also be a by-product of extra Lab Total, that the Magi wishes to utilize.
What, how? Gaining exposure XPs?
Yes, if you have no Summa or Tractatus, even gaining Exposure XP is god, enough to raise your Art to 1, and having a formulaic spell, makes it easier to cast in an adventure, and then you can spend Adventure xp to improve it faster.
Ok. I'd just trade some vis to get a handful of pawns of the Form I don't have books and study them. These are more XPs, but on the other hand would I end without that low level spell.
Studying from vis will indeed give you more xp, but that assumes you
a) Have the necessary vis
b) Don't need the vis for anything else
c) Aren't worried about the risk of botching when studying from vis
I suppose if I was doing a lab activity to increase one of my arts, I wouldn't rely on exposure, and instead experiment with a high risk hoping for a discovery.
That's an option, but his Lab has the flaw that he can't experiment or bind familiar. He is a Bjornaer, so the bind familiar wasn't really a loss.
And we have no source of Perdo Vis to study.
Magi who want to reliably cast low level spells but lack the art, or have it and want to cast without sound or gestures, or often visit Dominion auras.
If you have low scores in the relevant Arts, and you want to cast a spell without words and gestures, or in a Dominion aura, you are usually actually better off casting it as a spontaneous spell than as a formulaic.
Reason is that all those big negative modifiers are to your Casting Score, and thus get divided by 2 or 5 when sponting the spell.
Your math is off. What you write could conditionally be true but is commonly not true. Look at the math:
Formulaic: (Sta + Te + Fo + Aura + Voice/Gestures + Talisman + roll) + special = target number
Fatigue spont: (Sta + Te + Fo + Aura + Voice/Gestures + Talisman + roll) / 2 + special = target number
Non-Fatigue spont: (Sta + Te + Fo + Aura + Voice/Gestures + Talisman) / 5 + special = target number
So with all the same values, you must always reach a higher (target number - special), where special is the rare thing that adds after division (like Spell Foci) unless (target number - special) ≤ 0. We must remember that the roll is within the numerator of that fraction, too. So the only time the division would get you closer to the target number is if the numerator is negative. If (special) isn't big enough to get you to the target number on its own, then you need a positive numerator, undoing the value of the division of a negative numerator. Those leave us with the only case where you are better off sponting:
If you have some special thing that adds after division, that special bonus is greater than the target number you need to reach, and your Casting Score is negative, only then are you better off with a spont.
That's a pretty rare special case.
Edit: I forgot to add that, if penetration isn't an issue, then Formulaic essentially gives 10 points of (special) on its own due to being able to miss the target number and just spend 1 Fatigue. That then noticeably reduces further when the special case applies.
Even if it's true, for those Magi with Flawless Magic, it's usually best to research those spells, not for the +1 casting bonus from Mastery, but for the fact that Mastery can give you options you might not enjoy otherwise.
My magi researched a PrIg5 touch spell to casue fatigue. His Mastery allows him to Multicast it, so he can inflict two fatigue levels in one round, either both to one person, or one each to two different people.
In addition to all these reasons, knowing a spell gives a bonus to the lab total for learning 'similar' spells. So low-level spells function as stepping stones towards more powerful spells.
Tell that to a Magus with the Strident Gift.
Get your parma up to 20 and share it with the full clientelle?
If not, there ought to be some faerie pub where not everybody minds.
Drink with the faeries, spend 70 years washing the dishes at the back of the pub...