It's like a quadratic curve. Amount of work needed vs the resulting visual quality. Eventually you get to a point where it's just too much work to get it looking like 1% better, that's when I call it finished. like so: When you improve as an artist the curve changes and you can keep it up for longer, since workflow…
As for me, if it reads from a distance the way it is suppose to be seen and understood then that is when I know it is time to move on. It is common sense that you know you are spending hours on something so tiny and yet unseen from a players/ viewers point of view. You know deep inside that you are wasting time... And I am…