My info is a bit dated, IIRC, I spent about two hours a night on the stuff, unless there was a paper or project that would be about 8-12 more hours per week. There were group sessions…weekly?, but mostly it was on my own time.
I was working and had young kids (not drilling at the time) and it was a lot of work to get an A-. For the final module, I didn’t care for the professor or subject, family and work life picked up, and I did pretty lousy. Didn’t finish all the reading, missed a few group sessions, and wrote my final on info/scenario that had changed two weeks earlier. I felt horrible, and thought I’d fail or should quit.
For me at least, I learned I could work really hard to get an A, but it was pretty tough to get a C (I got a B- on that bad session).