Why does everyone preach about how good group sessions are? It could also be a really good way of wasting a couple of hours.

In my experience it was just a way for people to bounce off things they didn't know about the aircraft to begin with. That just didn't make sense to me. I locked myself in my room read my books, not the notes or cheat study guides, my actual manuals. I turned out fine, some guys that were studying with each other for hours had problems.