Definitely depends on the subject. For example, for my architectural history class group studying was great because we could discuss the buildings and time line and it would help everyone keep the sequence of events and classifications straight.
But for something like structures, which is more math and physics based, basically all you could do was practice problems. Unless you were unclear on an equation or something, there was really nothing to study as a group.
So yeah. Really good idea for some classes, kind of un-needed for others. I don't think it's ever a bad idea, unless your group is being very unproductive. Then it just turns into a waste of time, ya know?
--
http://img.imgcake.com/crimjpgpe.jpg Mo' buildings mo' problems
ocean kinda grew on me like a flesh eating ...fungus. -BIGPUN9999