I have been wanting to paint a cow for quite some time. While going through my stacks of paper to use there was another odd size one that just said "cow head" to me. At the time I put my signature on it I thought it was finished but as I look at it now I see a number of improvements I could make, and that is a good thing. It means I learned something. But now the decision, do you go back and work on it some more? or do you leave it as is and apply what you learned to the next one?