sidenote: it's impossibly hard to make a really good movie. I feel like this is mostly because the studios get in the way and ruin everything. the great movies/tv shows- are the ones where the creator/writers has complete control and freedom.
Example of a studio almost ruining a movie- if you've ever read/heard the stories about how the studio got in the way and tried to fight Francis Ford Coppola on everything- and how he had to jedi mind trick them into making the movie a period piece, casting Brando, casting Pacino, and keeping his job- it's fascinating stuff. All the odds were against Coppola and the deck was stacked against him. He only got the job after literally like 10 other big-time directors turned the movie down- and he was a young and upcoming director/screenwriter who they felt they could get on the cheap and whom they could dictate and boss around. Boy were they wrong. He had to threaten to quit in order for them to make it a period piece and true to the book- studio wanted to shoot it taking place in the 70's in St. Louis to save money- and not the 40's in New York City like the books. And even after they finally agreed to make it a period pace in New York- he nearly got fired every single day the first month of shooting.
Coppola wanted Olivier or Brando for the lead role, Olivier turned it down and the studio refused to even discuss Brando. Coppola got the studio to agree to at least let him screen test Brando. The studio agreed on the condition that if they cast Brando- he had to audition for the role, put up a bond for $1 million personally guaranteeing his behavior would not affect the movie and oh yeah- he had to do the movie for free. Coppola had to trick Brando into thinking they were doing character tests and not auditioning him- so he went to Brando's house with a camera crew and little props like cigars and italian cheeses & sausages- and they shot Brando transforming into Vito Corleone by putting make-up on his face to make himself look older, putting black shoe-polish in his hair and stuffing his cheeks with kleenex tissue. Once Coppola showed that footage of Brando as Don Corleone to the studio they caved and let him cast Brando.
Coppola wanted Pacino from the start and the studio wanted Robert Redford or Ryan O'Neill. Talk about literally ruining a movie if that casting choice is made. Studio said no to Pacino- and that you have to do screen tests. The studio spent hundreds of thousands of dollars on screen tests for Michael, only to have Coppola wind up casting who he wanted in the first place- Al Pacino. The studio was pressuring Coppola to replace Pacino so much the first few weeks of the film- that Coppola rearranged the entire shooting schedule to move up the scene where Michael kills Solozzo and the crooked cop just so he could have that on film to send the studio and get them off his back. That worked- after that the studio stopped begging him to fire Pacino. After the movie was done shooting they pressured him to cut the movie to 2 hours, not a minute over or they would take the editing out of his hands. His final cut was 2 hours and 50 minutes- when he told the studio that- they freaked and made him cut it down to 2 hours. So when he showed them a cut that was 2 hours exactly, studio flipped out and said they wanted to take the editing away from him. So Coppola put the 50 minutes back- studio saw it and they couldn't deny it was great- so they let him keep final cut.
Despite all those obstacles- film turned out to be freaking amazing and it's because Coppola stuck to his guns and it was his vision- and he didn't let the studio push him around. If he let's up on any of those sticking points- the movie is a disaster and not a masterpiece.
Moral of the story: the studios suck.