By "nuances of each position" I didn't mean position=technique (as often seems the case in the BJJ world...) , I meant literally each position, as in guard, sidecontrol, etc. I'm not saying that an instructor should cover every detail of each technique he shows, I'm suggesting that maybe every once in awhile he should take a class and teach things like "here's a few ways you can break head control and posture up in guard, and here's what your opponent might do to stop you." A focused set of combinations and strategies detailing the battle for position within the position.
In my experience, these things just come as side comments while the main focus is to teach a technique, drill a technique, teach a technique drill a technique and so on, and then just start rolling. In the better classes, the instructor actually teaches combinations of techniques as responses to your opponent's reactions, and I think that approach should be applied to just general movement within a position too. There are plenty of classes where, for example, we learn guard armbar, then armbar->sweep if your opponent stacks one way, or another sweep if he stacks another way, etc.
IMO some classes should involve drilling simple responses to the little things your opponent might do, like hooking a leg as they stand and so on. Right now, the only time we ever do that is because we are drilling a handstand sweep, we never drill just the positional responses.
For example, when Bravo is teaching his rubber guard game, he drills things like punching the arm through to pin your opponent's hand to the mat. This isn't a submission, it's not a sweep, it's not really a 'technique', but it's a significant nuance of the rubber guard position that is very helpful for people new to the position to keep in mind.
EDIT: Sorry Ender, didn't notice your post, but that's exactly what I'm talking about. Every class I've been in is exactly like you said, drill a bunch of techniques, then roll. The fact that your class also includes just positional drilling is great. Like, I imagine a restricted rolling where you're in halfguard or something, and there are no sweeps or submissions: the only goal for the guy on bottom is to get on his side and get the underhooks, and the only goal for the guy on top is to flatten him out and cross-face him, and so on.