Yes, that’s what I think at this point. There is no effect of the study group except as a support group. (That’s all it was for me when I was a student and joined the self-organized study group.)
My self-organized study group was quite a mix of characters, and while I don't doubt that a couple of my friends's grades did benefit from having me there to help them out, I do definitely think that most of the stuff I remember learning there was outside the boundaries of what any of our parents would have approved :)