I agree with Miss Hellman…also agree with Hemingway when he said there are no masters, only apprentices in writing.
Personally, I've never met a writer who was completely satisfied with their finished work. Yes I have met quite a lot of writers over the years.
In my opinion a good writer will always feel they are never done and their best work is yet to come.
I have not written a novel…only published academic papers, written for magazines etc, and I have always felt (even after having been told it is good) that I could have done a lot better..