I was reminded of this a few days ago when, out of nowhere, I thought of a slight tweak to a chapter that strengthens the plot of the novel I'm working on right now.
Mind you, it wasn't even something I was consciously pondering - yet I recognized right away it made the story better.
It's a reminder that, if you're working on a book --- or simply thinking about writing one --- to let the muse have plenty of space to roam.
Keep a notebook nearby - or a digital voice recorder if that is more your style. Then log those tidbits so they're readily at hand.
You'll be thankful for that later.