You always want to quit while you are ahead. You don't want to be like a fighter who stays too long in the ring until you're not performing at your best.
If you ever go to a music session, you'll notice that the musicians can sit down and start playing right away, and everyone knows what to do. Of course they're reading it, but the conductor can tweak little things, and you can take that back to directing motion pictures.
I've always felt that if I examine myself too much, I'll find out what I know and don't know, and I'll burst the bubble. I've gotten so lucky relying on my animal instincts, I'd rather keep a little bit of the animal alive.
You have to steal a lot. You have to have a criminal mentality to be a film director.