I'll admit that certain classes are frankly boring, typically the more realistic ones such as math and history. I think the reason why things kinda slow down during classes though is that for the most part, everyone here is a fighter; we focus on fighting and most of our skills are revolved around that. Take us out of such an environment and there isn't really much we can do. Given the chance we'll fight or at least interact with our characters in more personal ways, going through actual classes were we're expected to sit and listen is, of course, pretty mundane. 

That being said I do sort of enjoy the chances of seeing how our characters work outside of the field of battle. What kind of person they are when they don't need to be fighting, or when dealing with tasks that don't involve violence of some sort. That puts off a lot of people who don't want to do anything but fighting, but that could speak much about your character too. As for how the grouping is done, well, classes are classes. unless students are expected to exchange between intervals, it'll only make sense that they end up hanging out with the same group of students everyday.