Really, what takes the longest is coloring. Rendering is relatively easy if you take advantage of masks/alpha-locking layers and gradients. (digi-drawing jargon)
Don't have to use high-end software either (tho I do use CSP, I used to use Autodesk Sketchbook which is free and easier to use)
If I can ever figure out how to stream a quick draw, I would love to do it...