There are two ways to match audio, either you do it by ear and by matching the waves forms, which means sometimes the people doing it make tiny cuts so that the audio stays in sync.

Alas it’s wrong because a) you alter the original audio b) from one master to another, the audio never match exactly because it wasn’t captured the same way, but when you view it with the image, you won’t notice the tiny ms differences.

Or you do it like I do, which is syncing the audio by matching the image to the available current master.
In that case, you don’t have to worry about the waveforms being exactly in sync on every version you sync. It worked for the source master, then it will work for the new one as the frames of the film are the same.

The only modifications are adding missing audio at the end of reels or beginning, when the source master misses some footage.

I advocate as a rule to always sync by frame matching. It works 99,99% of the time.