Sure they are. But I'm trying to establish a bit of internal consistency. Generally one has been able to do that with the rules, certainly one can do that for apprentices. We know, for instance that people of standard means get 15 xp per year must work 2 seasons, people of Wealthy means get 20 xp and only work 1 season and the poor get 10 xp and must work for 3 seasons. Working it out, a Wealthy person gets 2 xp of exposure for that season of work, and 3 seasons which average 6 xp for a total of 20xp. Average standard of living gives 15 xp, 4 of which are exposure and 5.5xp each of his two free seasons. Finally, the poor person gets 6xp of exposure and in his one season of free time he gets 4xp.
The only ways to make it internally consistent are to assume that the average teacher has Com+Teacher+Virtues=12, which I find to be incredibly unlikely. Even if we set Teaching at 5 add in an appropriate specialty, Com+Virtues still has to equal 6. I can't really suspend my disbelief that this is an average teacher. Especially when we presume average is a score of 0 in a Characteristic, it becomes even less plausible.
The artifice of seasonal doesn't change. We know that the craftsman doesn't work for two seasons and take two seasons off. We do know that over the course of an entire year, his time is spent by doing two seasons of work, with two seasons free to do as he desires, such as improving his workshop or whatever. And in the scheme of things the artifice of the seasons doesn't have as much of an impact on Abilities nearly so much as it does on Arts.