Here’s the thing about editing and polishing a paper or novel. You can edit till the cows come home and hell freezes over and still find things that can be tweaked here and there. You can change the cadence at which someone speaks by adding a comma instead of a period. Add or subtract an adjective. Change the spelling of someone’s name. All kinds of stuff may come to mind the more time you or your editor reads through.
Things really get interesting when more than one editor is reviewing something. Both may be amazing editors, but they can still disagree on how or even if something should be changed.
Sooner or later you have to declare yourself done or eventually what you wrote will no longer be what you meant.