I do have the luxury of CTRL+Z, but I can only backup about 20 steps. Since I like to use the spray paint tool set on barely anything comes out, I've sprayed 5 shots before the difference becomes noticeable. I have to be careful. I've rage quit on a few after a couple of hours simply because of nasty errors. The free form flowing pieces are easy to fix up but if I'm working on eyes, then notice I forgot to add a new layer and I've been messing up the white... I'm pissed. I've done that a few times.