When 2 of the people from Pixar(one modeler,one animator) came to my college to do a workshop on 3d animation production.They took us through thier entire pipeline from storyboarding to final video editing.The only thing you could consider to be post work was the tweaking of contrast and levels,or compositing layers(which was done in the final video editing).At no time did they go and paint,frame by frame stuff that was messed up.When I say postwork,I mean painting in things that are not present in in the render.So if the guys from Pixar lied to my whole class(not to mention they brought in scene files from "A Bug's Life" and showed every step taken.)And yes tjohn,I know they dont use C4D,thats my preference.