Originally posted by Benoit

...I also beleive that you become better faster if you play in a band. There are some things you cannot learn alone...

Being with other people kinda forces you to get more disciplined.Coz you're considering them too.And if you're gigging,you need to rehearse together,(opposed to just playing for the sake of playing)which I think means more practice time.And being on a stage,no matter how small,is not the same as being in your basement.Or on the stage in your basement,:)
A band definitely helps.
I'm not in one myself yet,but I've been involved in other theatrical perfomances,by myself and in a group,so I can appreciate this fact.