On the X-Men films, people are always throwing out ideas and trying to get the shot to look the best and make the most sense, and to get it done efficiently. Everybody collaborates and everybody is very open to new ideas.
You can't plan your character arc - you have a vague idea, maybe, but I'm constantly surprised. Sometimes actors in films will play the ending of the movie, or even the middle, and you know where it's going - as an audience member you can read the actor.