Like every novel writer, my goal is to get to the finish line with a manuscript I’m proud of—one I’ve spent weeks, perhaps months, carefully carving out before passing it along to my editor. There’s no greater feeling than clicking the blue send icon, depositing it into her capable, passionate, and at times over-the-top thorough hands (in a good way). It’s a rush of accomplishment.

Yet a nagging feeling slithers into the joyous moment. I should have spent more time on it—even though I’ve g...