Gary Ross spoke to Entertainment Weekly about his book Bartholomew Biddle and the Very Big Wind and leaving the Hunger Games.
”I didn’t feel that I would have the time for the way that I work to do the movie justice,” he says. “I wear two hats. I don’t wear one hat. When you write and you direct that’s a linear process, it’s not a simultaneous process. I would’ve had to have written a script and prepped the whole movie in four months and on the first movie that’s a process that took me eight months. And I thought [Catching Fire] was a more difficult adaptation, not an easier one. I didn’t really feel I had the time I needed to live up to my own standards. And I haven’t had a moment’s regret. It was absolutely the right decision and I’m thrilled about new challenges.”
Source: Mockingjay.net