While going through links on illustrationfriday.com, I found another group of collaborative artists: Limon Four [M.Limon, S.Limon, J.Limon and N.Limon. Yes, they're brothers]. They sometimes work on the same page, and sometimes on different pages and combine them. On their work & progression page, you get to see what each artist did, in what order, as well as the final 'finished' piece, like this:
What I like best about collaborative work is that it really is a lot of fun. There is something special about starting something and having another person transform it to something totally different and unexpected. It sort of makes you let go of the need to make it 'perfect' from the beginning, cause someone else is gonna jump right in and change it. Spontaneity. That's the word.
Ok, I'm not a quote person, but I found this quite relevant. So, before I change my mind about it, I'll post it. And yes, make it italic: "Creativity arises out of the tension between spontaneity and limitations, the latter (like the river banks) forcing the spontaneity into the various forms which are essential to the work of art or poem." Rollo May, The Courage to Create, 1975.