Yeah this isn't a bug, this is intended although still a work in progress. The problem from a game design perspective is that if you go from having 14 (or fewer) actions per loop to having 50+ actions in a loop, that long loop lets you level up skills way too fast. So the ~20 units of time in an academy class only gives you about 5 units of skill progress. I'll be tweaking this more, and some other methods of leveling might even need to get slower to match up more reasonably.
I will mention that there are several skills you can only learn at the school, so don't miss those.