Hi @opheliafu
I am not an artist at all, but my dad is also a painter. What I have learnt from him is that an artist is never satisfied with his/her work. I would think the painting is perfect and beautiful, but then he still would like to change. I have one particular painting of his hanging in my house (I have a few of his paintings) and every time he comes to visit he wants to take the painting back to change it. He also has one painting that he never completes and I think he never will.
All of the best with Big Bob