Many authors find proofreading and editing to be physically and mentally exhausting. It’s possible to make the process less of a chore. I list a few tips in my blog post, “The Joys of Editing” (https://wp.me/p30cCH-L1).
An emotional challenge may also exist, as the time to publish approaches for an Indie author (or the time to submit to agents and editors, for those who are traditionally oriented). How can an author tell that it’s time to let that brainchild take its first toddling steps into literaturehood?
Keeping track of the chapter length helped me know when I was done with editing, because there came a time when revising things didn’t significantly affect word count: There’s usually more than one good way to express something, and those ways don’t often vary much in the number of words they use.
I knew I was done proofreading the manuscript when a full reading could find an average of 1 error (preferably less) per chapter. That would add up to 34 mistakes (preferably fewer), which constituted what I felt was the irreducible minimum for a book that was close to 200,000 words long. That doesn’t mean they were the last 34 existing mistakes, because I knew I’d still miss finding errors. It just meant that despite my being a perfectionist, I wasn’t going to let the job of proofreading drive me nuts. (I’ve found as many errors – and even more – in “professionally edited” books put out by traditional publishers.)
No job of parenting ever comes out absolutely perfect: just as most children don’t leave home to become promptly and persistently wealthy and celebrated, most books don’t leave their publishers to garner instant and enduring fame and fortune for their authors; nevertheless, chances are that the outcome will be reasonably good in both cases.