A director is a kind of idea and taste machine; a movie is a series of creative and technical decisions, and it's the director's job to make the right decisions as frequently as possible. Shooting a movie is the worst milieu for creative work ever devised by man.
And then there was Marion Brando, against all the odds, cast in one of filmdom’s juiciest roles, as mob chief Don Vito Corleone. He was eased in, despite stiff opposition from the studio brass, because of the advocacy of a thirtyish fan, Francis Ford Coppola, an Italian-American who happened to be the director of The Godfather. Once he got the part, Brando in turn helped Coppola maintain camaraderie during the frenzied three-month shooting by kibitzing with the cast and establishing a fatherly relationship.