I think this is interesting, but I'm a little confused on this part:
If there are four people who draw, then two could sketch and do flats, and two could color and do lineart so that the colors are nice and clean.
It might just be a weird 'me' thing, but from my experience a person does the sketch and line work while someone else might do flats/shading/backgrounds/etc.
Separating the sketching from the line work is an odd idea to me because the sketch is the lead up to the line work. Though maybe by 'sketch' you mean something like 'concept design' or general layout of a scene?