there's a point at which rendering no longer accomplishes anything, and this varies depending on the purpose of the work, if any ('for rendering practice' is a valid reason). You may want to try locking yourself to a very specific timeframe in which to do one picture, if you're the sort of person who won't just freak out over the impending deadline.
Originally Posted by eyestrain
in short time spent actually has no direct relation to the value of a painting and may actually make it worse, but you knew that, I think
(also you may want to abandon the term 'cheating' as it doesn't really exist in art*. I mean, digital art itself was thought of as 'cheating' for a long time. just learn what you need to learn)
* if anyone's got a counterargument, smack me with it please
o/ i'm a weary lurker / singing my song of loneliness /o