You paint things over and over???...
Davinci was an impatient "sketcher"...with only a few paintings to his name.
Not always do I paint things over, sometimes I get it right the first time and that is the best but I have painted things over more than once or twice.
I also take failed paintings and paint over them and reuse the canvas/board for a totally different painting. All artist do this. There might be a failed painting under every success. :)