If you haven’t worked with an editor before, you may be disconcerted by the amount of editing that has been done.
( Source: Daily Writing Tips | 5 Tips on How to Work with an Editor )
Having added an editor ([biased] and a great one, at that [/biased]) to our team, these tips ring very true.
My favorite of the bunch: 3. Pick Your Battles. Your editor know more about these things than you do. Let them do their job and get on with it.
If you feel you're questioning the same points over and over again, build a style / grammar guide specifically for you. Any breaks from the style guide will have to be discussed and agreed upon.
After working with an editor over the past few months, and building a style guide to reference when needed, I can't underline the editor's role enough in producing professional copy and a better internal collateral- / campaign-building process.