It seems to me that the more cohesive a group is, the better and that some groups are better than others and some leaders are better (or are a better fit for some individuals) than others. Additionally, like some have already said, sometimes the group experience would be more suited for some than others.

I bought that book when it first came out and recall REALLY enjoying it!
I WISH I could locate it to re-read it...more than likely I gave it to someone.
It is one of the ones that a person might want to re-read. I have suggested that people read this book when they reach a "milestone" of some sort.

Wishing you well...I hope the book will be helpful and comforting.