Most of the films I've done were ruined in the postproduction, not during filming.
I'm in awe of directors like the Coen brothers who can shoot their script and edit it, and that's the movie. They're not discovering the movie in postproduction. They're editing the script they shot.
Formulating the proposal is about 80% of the actual time of the process. In the end, the time spent filming, editing and postproduction is a very small proportion of the total time you spend in the production of the film.
When I was working at Trio, I was pitched 'Queer Eye for the Straight Guy' and I knew, whoever gets this, this is a game changer. When I started at Bravo in 2005, it was a hit, and Season 1 of 'Project Runway' was in postproduction.