When to say "All done novel, Robyn"

Back in art school I had a teacher who lived off snark. I usually laughed when he insulted me...until that one time when I really cared about the work. "Robyn, you're turning this in? Finished and signed? Oh, that's too bad." Not even all that biting, yet the words wrecked me for days, or perhaps the lower grade took the bite out of my pride.

Obsessing over the work until you run it off the rails seems to be the over-correction most people make. With writing, you don't want to suck the life and energy out of your novel. DYI editing books spout endless rules, cite the mistakes of famous authors, and finish their damning point saying, "If you're clever, you can pull off a certain amount of rule-breaking...p.s. you're not clever enough." Hell.