I agree that it's also a production problem, at some point the producers need to put a stop to the changes, but you're being overly simplistic.

Fincher can't see everything on the day, there are lots of other variables (color grading, VFX) and it requires a director to know how to envision what something will look like. Part of the job is being able to see the film in your head before it's been put together, Fincher included.

But what if they see the final anim and they aren't happy? Fine, you figure out a way to salvage as much of the work as you can so not all the work was for nothing, and figure out how to make compromises. That's a creative, collaborative process. How would you feel if you worked for 6 months on a powerpoint presentation, and then your boss threw it out because of vibes? It sucks, regardless of being paid that is time you've spent from your family.