How much of an original script survives to filming? I assume that huge swaths of dialog gets reworked as more people can workshop the scene and get a sense of characters/timing/whatever.
It depends on the film. George Lucas was reworking dialogue and scenes daily while filming the original Star Wars but the overall movie should mostly be set in stone by that time. But big changes can happen. For example, Ben Kenobi was initially supposed to survive the battle with Vader. It wasn’t until filming was already underway that Lucas, at Marcia Lucas’s suggestion, decided to kill him off.
