At several points, there can be dozens of people who need you to have an answer. Your job as director is to tell everyone if what they're doing is within your vision. You always have to be able to convey that vision to everyone making the movie with you. The question could be about an actor's character, and if their improv or idea works in context with the overall story, or your beliefs about their character. It could be making the decision to move to a cover set because the forecast is rain. I make sure to surround myself with smart and highly competent professionals, and then take everyone's advice. I like the idea that's best for the movie, even if it's not mine.