Beware of anyone who says they know. Trust me, they don't, or they wouldn't have to say they did.
I'm amazed that movies ever get finished at all - much less come out good once in a while. It's an awful lot of work and it can go wrong a thousand different ways.
This is like the telephone problem - no one wants to have the first one. But we are seeing a lot of people who want some sort of technology to solve the spam problem.