"The road to excess leads to the palace of wisdom... for we never know what is enough until we know what is more than enough." -- William Blake
A student once asked me when I knew an artwork was finished. I responded that sometimes the artwork was finished long before I stopped working on it. There is freedom is taking an artwork beyond its limits. No, it doesn't necessarily work out, but it does teach you what is enough. It also teaches you to feel the work. Early in my career I would stop working on a piece out of fear that I would ruin it, not because I truly felt that it was enough as it was.