Old members of RateMyDrawings.com and I collaborated with a referenced image, but we ran out of ink so detail isn’t very defined. We weren’t assigned certain roles, but we all shared the ink layer. RMD has a system where ink is held at 100% and after a certain amount of strokes or usages, the ink will be depleted. No further action is allowed unless you submit this art piece to the site exceptions of clearing the entire image. Also there are no ‘undo’ buttons so if there was a mistake, we’d have to overwrite the error. My contribution is particularly low, but I think these artists also need more views.
You can view the full time lapse: http://www.ratemydrawings.com/chat/gallery/91653.html
Also if anyone is willing to join the RMD site, please do. The community definitely needs to showcase digital graphic artists.