I try to limit my Bryce work to a few hours, though I allow myself to render overnight, since it works without me having to be at the computer. If I spend too much time on any one thing, then the amount I get paid to do the art becomes smaller and smaller when calculated by the hour, and I can't move on to the next piece right away. If there's anything I have to fix, then I do it in post. It's faster, easier, and better looking.