Is a book ever done?

I just sent my page proofs back to my editor with final notes. My notes were minor, but they are also a reminder to me of how very much goes into making a book. Who would have thought at this point in the publishing process that I'd still have things I wanted to change? Granted, the changes I sent back were a word here, a line there. But still, after several rounds of edits — my agent's, my own, my editor's, my copy editor's — I still found an awkward phrase or too that needed reworking.

My q...