I always start at 400 just to see what's what with pitting/staining....

Some times you must go lower to get it all... and that doesn't even start to mention belts, and compounds... we are still just talking sandpaper here.

Whatever goes deeper in the metal determines what is left showing...

Murphy's law with razors however states explicitly that the stains/pitting will be deeper than the etching

Restoration is sometimes a balancing act between looks / stains / steel integrity