I'm having trouble reconciling "what I would do as a magus" with "what seems to be reality." Specifically I don't see why there are not dozens of Tractatus on every Art circulating among any magi who want to reach high levels in an Art.
The initial idea was a Bonisagus thesis called "The Climbing Body": as one limb propels the other upwards, only to be propelled by it in turn, two magi can teach one another and be taught thereby. If you have ten Tractatus in a topic, and two magi (Alpha and Beta), Alpha can read the ten Tractatus, teach Beta up to her level, then Beta can read the ten Tractatus, and teach Alpha to her level. Additionally, as Alpha and Beta reach [say] level 30, each of them can write six Tractatus, and they can learn/teach/learn/teach that way.
It is plausible that any magus doing this would be publicly known as "still an apprentice" or clever, childish phrases would be applied to the two of them.
However:
Once level 40 [say] is reached in an Art, it takes about one pawn of vis to gain one XP in that Art. Reading one good Tractatus gains 8-10 XP in that Art. Imagine a studious, Book Learner, Bonisagus who has access to the Great Library at Durenmar, with thirty Tractatus [of varying Quality] on, say, Creo. Someone with Book Learner could gain [if the average Quality is 7] 9*30 = 270 XP. Level 50 takes 650 XP to reach : 270 from reading those Tractatus, 210 from your study buddy reading those Tractatus and teaching you, 200 from a Summa with a starting level of 10. That's 680 XP with not a single pawn of Vis used. You have to spend a lot of time teaching your fellow magus and vice versa, possibly half the "study" time.
( And then someone can write a level 25 Summa on Creo. )
Here's the next situation: You round up the resources of your Covenant (five other magi) and get them to each write two Tractatus on Creo. You now have ten Creo Tractatus, all new, none written by you; worse on average than Durenmar's, since these were not volunteers, but that's 60 XP of Tractatus. You now trade with, I don't know, Val-Negra for ten of their Creo Tractatus and Coeris for ten of their Creo Tractatus. You have ANOTHER thirty Tractatus and you can reach level 50 on your own.
... and write ten Tractatus on Creo for trade.
In the last 300 years, why have there not been dozens of Tractatus written and commonly traded on every Art? Any Magus who wants to be an expert in an Art or two should write and trade them.