Drawing on a computer is insanely easier than traditional media, if you know how to use your programs well. But it can still take a long time, and I'm thinking at least one part could be made a lot faster, and that's cleaning up sketches.
Anyone who draws knows what I'm talking about. Your first draft
is all rough and has sixty thousand small lines everywhere. You have to carefully erase some, or if you're on a computer, you can retrace on a new transparent layer. This is a brilliant way to go, because it's non-destructive. But it takes forever.
Let's say you're drawing a circle freehand. You can do it, but you're not going to do it in one continuous line. So let's say you make a fourth of the curve without lifting your pen, but it's mad sketchy and messy. It shouldn't be too hard to get some math working behind the scenes to estimate a vector curve for what you've drawn. It could save it to a new layer, or even just replace what you drew.
On curves, per se, your lines will all intersect, being tangential to the overall curve. That can't be too hard to simplify. If your line is more straight, I'd assume it would be even easier. For corners, you might want to disengage it to avoid problems.
You could assign some hotkeys so you can switch between modes: One mode to make your cleaned-up line connect to the last line you drew (for drawing a circle, per se), one to keep them separate (if you're drawing some small details, you don't want them merging together), and maybe one for connecting it to the nearest line (because some details get drawn out of order). Keep an undo button in effect and it's pretty much impossible for you to mess up. You might have a hold-down toggle key, so while you're holding it, your lines are all being fused together into one smooth line. Then you let go and you can draw a new line.
This would fully eliminate the entire cleanup phase. You could go straight to shading, or, if you prefer, bucket filling: since all the lines are solid, you avoid those tiny spaces that can't be filled properly (anyone who's worked with MS Paint probably knows what I'm talking about).
Another plus: since it's all mathematical now, I'd think you could save it as a vector file and blow it up as large as you like.