Sooner of later you’ll get to a dialogue problem you can’t repair. Say the noise interfering with a line is the same on all of the takes, so alternates won’t save you, or that the actor is so annoyingly accurate that she always says the line exactly when the dolly starts to move. Maybe there’s no close-up coverage of the off-mic wide shot you’re trying to fix, or the take chosen by the picture editor really does have the best acting despite the F-15 flying overhead. There are a million reasons for rerecording dialogue.
Replacing What Cannot Be Fixed
Everybody loves original production sound, so there’s no point discussing the magic of the sound from the shoot, when the actors were hyped and in character. There’s always the concern ...