Scratch tracks and temp SFX expose pacing problems line alone can hide. We embrace ugly sound if it saves weeks later.
Board revisions then chase the beat instead of the other way around.
Editors get a locked BPM map for action scenes so board artists know exactly where impacts land. Silence is treated as a sound event too — holds breathe better.
When music enters later, stems are written against the animatic spine so orchestration supports motion that was already approved.