I guess it would be up to the people who want to sign up....I would get a feel for what they think.
But in keeping it on the smaller side, like I had mentioned in my other post...what about one small and one medium, with any more to be determined between the partners themselves?
I think that sounds good! One small and one medium seem to be a good fit for me. I don't seem to stress as much, and I get to make more than one thing! (I can never seem to make up my mind on what to make my partners, I always want to make them everything!)