It's amazing how many odd things one notices once the paint starts going on. Who'd have guessed I attached the harness to the wrong side of the horse-drawn sleigh?
Once I painted a scene and I put two hats on the character. One on his head and one in his hand! No one noticed until the book appeared in print!
This is why the eraser was invented.
It's quite true that I probably erase almost as much as I draw. That comes from being a perfectionist, although in my sights I'd say perfection is only a distant hope.