I think part of Tellus' point above was that those Com +5 politicians probably do write tractatus - or atleast did in their youth, as a way of gathering a reputation - and a way of buying votes.
I'm also not quite sure I agree with the assumptions made in your program above, but nothing major.
Not all junior magi stay in a summer covenant with the resources to do this, though. Sometimes they go out and start a new covenants, and have a whole mess of other things to deal with besides writing tractatus as covenant service. This is a very real issue for character motivation. If a character writes a tractatus to fulfill covenant service, who owns the tractatus? Who then decides how it is distributed? I would think that it is the covenant, but it might need a legal test at Tribunal. Not everyone is going to want their writings to belong to someone else, especially if they are a junior member.
It may be an expensive way to buy votes, but certainly, you're right, it would be good for building a good reputation.
I was trying to develop a quick and dirty method that would give probabilities similar to a bell curve. I'm not sure if I got the inflection correct for only 11 data points, but it's a rough distribution in any event.
These have generally been spring covenants.
Yes?
Ths has generally been assumed to be the covenant.
It is a covenant service - meaning how you serve the covenant ad are permitted to be a member, thus allowed to draw upon shared resources.
Obviously, but if we go back to your own comment about spring covenants, you'll probably be a founding member yourself.
And thus is all comes around, again, to how the SG wants to define his world. If the SG wants to make writing books or getting books to be a choir, then it will be. Book Learner is only as good as the supply and quality of the books. On the other hand, Good Teacher is totally in the player's control and can be quite powerful if the players want to put some time into teaching each other.
There is a spirit of cooperation that seems to be inconsistent to the setting, in that a magus will willingly give up their knowledge in perpetuity to the covenant.
There are plenty of other methods to provide covenant service, and also retain access to the knowledge. Writing a book is easy for the player, but I contend that this is a metagame construct that most characters wouldn't really be interested in. Certainly not most of my characters, and I tend to create characters who are cooperative. I'll make an item for covenant service, I'll probably never write a book from covenant service. For all those who are capable of doing so, one has to wonder if you examine the character motivations, would they all so willingly submit tractatus as their means of satisfying covenant service? I'm thinking no.
It's a choice, it's a character/player choice, but when I'm creating a world, I'm thinking about the motivations of the character, and not all are so charitable or giving, and I can see many going through with alternative service than making books for others to reap the benefits of...
As far as what books are available, how common or rare they are, and what a character has to go through to get them, I think it's important to remember that you have to balance both sides of the equation.
If it's harder for a PC to get a commodity because it's valuable, rare and/or difficult to acquire. Then another PC who can create said commodity has a great deal of power.
So for instance you can say that Magi with a Com+3 and Good Teacher are rare and writers with a Com+5 and Good Teacher exceedingly rare. And you can also say that even if characters like that exist they don't always spend there time cranking out Tractati. Then you can base the availability and value of Books on those assumptions in your saga and limit your characters access to books and resources accordingly. But then when a PC comes along with a Com+5 and Good Teacher they are going to expect the same compensation that the NPC's are getting. Never mind the possibility of PC's with an effective Com higher then +5. Which is quite doable by the rules.
Reputation. Fame. Legacy.
If you write the best introductory summas in the Order, being the first to max out one or more Arts, or Magic Theory, every apprentice will know your name for the next few centuries. If you accumulate an Art score of 20 or more and write a set of awesome tractatuseseses, you will gain fame for being expert in that Art, you will gain fame for furthering the Order, you will have many people willing to pay you for your books, and you will have friends and allies when the time comes.
I sense we are discussing past each other and, as ezzelino said elsewhere, I don't see any common ground. Where people see simplicity in setting up a book factory, I see a situation that is less simple, quite frankly. Not every magus starting out has Latin 5, quite a number have Latin 4, because let's face it The difference between Latin 4 and Latin 5 is one Art at 4 and another Art at 5. 25 Experience points to a new magus is not insignificant. And resources aren't always available to get to Latin 5.
Again, this is about assumptions. You're starting out with plainly different assumptions than I am. And even factoring into the equation all of the tractatus that could be written, not all of them will be on Arts. Quite a number will and should be on Spell Mastery for a lot of the common spells, especially combat spells and rituals.
All good points. But you can go even deeper with that line of reasoning. As players of a game we almost always think of our characters actions in a cost benefit sort of way. What is this going to do for my character what are the extrinsic rewards. And as you pointed out there are certainly plenty of rewards to come by with writing. However if players really want to pretend we are role playing these characters, we also have to think of the intrinsic rewards a character's efforts produce.
In short just like a character who has a high intelligence and affinities for magic theory loves lab work. So to should a character with a high COM and good teacher love teaching and/or writing. Sitting down and writing a book therefore is not just something such a character can do well it's something the character should want to do. And just like a well role played lab rat needs to be dragged out of their lab on occasion, the writing focused character doesn't need a story reason to be writing he needs reasons to put the quill down.
Certainly in a population of individuals who know for a fact that knowledge is power and language is magical there are a fair number of people who would be drawn to writing for writings sake. And certainly many if not most of the people want to write will be "good writers" and the greatest writers will almost certainly be among those who love writing for it's own sake. In the real world that's how you become great.
I can hardly emphasize enough how much I agree with this statement.
Although, for books there's one catch that allows you to keep good books away from your PCs, and at the same time avoid a Com+5, Great teacher character from getting queens of vis for a handful of tractatus. You have to assume that individual covenants are very, very isolated and the redcap network does not work nearly as well as it could (or as it's described in HoH:TL).
Gee thanks. 
Yes that works up to a point. If it takes seasons of effort to get books from another covenant it will lower the relative value of good books versus staying home and increasing your arts some other way. The rewards are still there for both sides of the market if the characters overcome that problem some how. And Ars provides many a tool for solving problems.