Recently I had to do this again. I started a painting and when it was mostly completed, I realized that it didn't really work in the direction of the new series I was starting. There were elements I liked, and some that I REALLY liked, but it didn't feel right. I decided that the whole piece had to go. When I showed it to some fellow artists, they wanted me to try and make it work since there were parts that looked so good. I kept repeating "Nothing is too precious that it can't be erased." After much arguement, I decided to give it one more shot to see if I could make it work. Nope, I still didn't like it. It wasn't going to fit into my series which meant it had to go.
I haven't started on the new painting on this panel yet, but not having to look at the old part and knowing that I have a completely clean board to work with already makes me feel better about the piece. So what's the moral of this story? Nothing is too precious that it can't be erased. Be willing to get rid of your favorite part of a painting for the sake of the whole painting. Make any sense?