David Yates, who is currently finishing up with the Harry Potter and the Order of the Phoenix movie, recently commented
on the length of movies that incorporate too many action scenes or visual effects, which overwhelm audiences.
Yates says that sometimes it is better off to leave scenes out if they help with the final product.
Sometimes they overstay their welcome just by that little, tiny percent. There's a sweet spot for running length where the audience comes out feeling elated, feeling they actually want more. Reaching that sweet spot takes a lot of discipline.
You just have to let things go, sometimes. It's amazing how you think you could never live without a scene or a moment, yet frankly, the movie's better off without it.