I've gone back and forth on this, but I get the reasoning.

It definitely depends on the density, but from an editorial perspective, it can be really beneficial for reference (at least for me)

I always ask writers not to do that until we do the dialogue refresh. Because once you see the art, you might tweak the balloons/captions/six, and split a balloon in two, etc. All of which is more complicated with numbers already set up. Or, dog forbid, auto-magically applied.

Yep I do this

I also will do whatever my editor asks, format-wise!

I totally get that. Panel numbering is more important, but I just aim for legibility and reference as much as possible and typically there will be an adjusted document that matches with the final art before sending it on the the letterer. But this format helps me keep track of that, too

How to Write a Comic 1. Stare at the blank page before you 2. Panic 3. Think about how to construct it in the best way possible to give the letterer the best possible roadmap so the only work they have to do is their beautiful textual flourishing 4. Repeat Steps 1-3 until completed