Keeping track of bridge position while changing strings

Buco

I'm actually surprised most people seem to do it one by one. I do that extremely rarely. I always like to give the top and the fretboard a quick wipe down. I used a pencil to lightly mark the line behind the bridge. But I erased it since I know roughly where it goes and if need be just nudge the bridge, it's easy.

I think it's been mentioned but you might need frets dressing or crowning.

You can deepen the string slot yourself easily. Use a light touch and a sharp knife or a piece of old string to make the notch deeper. I've read the notch depth should be 50% of the string but I've seen guitars that came from very well known luthiers with strings way deeper and sounded great.

juanderer

Pretty much what Wim said.

I don't find the need to mark the position (temporarily or otherwise) as the bridge leaves a dimple and/or scoff where it's set (at least til now - I haven't seen one that hasn't). I use that for approximate position and let intonation help me fine-tune it, ambiguously.

If I don't need/don't have the time to clean, I change them one at a time.