You get to use everything you learned in movie business. You talk to actors, if you do it right - and I haven't always done it right - you should be shaping the material all the time. And the other thing is, you get all the blame when you direct and it doesn't work. You get slammed. So that's another reason to know what you're making, why you're making it, and make it the way you want.
Login to join the discussion