I admit, I'm kind of neurotic about checking and double-checking...and triple-checking...my work for errors. But for something important, say publishing a book, it can be a lifesaver.
While going over Dead Locked one last time, I saw double. Two chapters labeled "23." My heart froze. Did I seriously mess up the chapter numbering? Sure enough, I had managed to get the ordering out of whack earlier. Not surprising since the chapters weren't in order since my first draft months ago. So I fixed that problem but then I was paranoid and checked everything again to make sure I hadn't missed some horrible, glaring mistake. I didn't catch anything else and I hope you won't either.
So this is my advice for today: If you want to check that important document one last time, do it. It could very well mean the difference between catching a glaring mistake or publishing your book with two chapters 23.