Huh? That's an awfully different take on learning. So...not studying at all for months means one learns faster? Well, it would certainly mean one would learn more things quicker if only because there is so much less one would know than a student who dedicates a lot of time to studying daily.
Realistically, that's how it works as well. Maybe you're a genius who picks things up in minutes, but for the vast majority of students, both current and former, in order to excel at any subject, they had to put in the effort. That meant that they spent a lot of time studying. If not that, then they gained experience in practical settings.
In translation to BM, that means that right now, more training frequency leads to more success because of the higher frequency of attempts. Yes, that's expensive. Ever try paying tuition for a high level private university? Why should an academy for the elite among nobility be any less expensive? Actually, the rates aren't so bad in BM's academies.
Now, if paying gold to study up isn't your thing, then leading infantry can keep your swordfighting handy, leading cavalry, jousting. The other skills have already been explained as to how they can be improved on the field. And that's also realistic. If you don't have the money or don't have the motivation to stay in school, you gain experience in the world.
So in short, it seems very counter-intuitive that staying away from the academy would give a better chance to improve skills. If anything, it should decrease the chances as one has to get reacquainted with the tempo of studying.