No such thing as too much postwork. No such thing as too little postwork. It's your art, whatever work or tools you need to realize your purpose is the correct amount. There are "purists" who try to do the whole thing in a straightforward render, and just as many who use a render as a starting point and wander freely afield thru any 2D software they fancy to modify the image until they're happy with the result. No two follow the same process. . . .