A book is never finished is what they say, and they're right. You get to a point where you have to be satisfied with the work. There will always be things to change, scenes or descriptions to add, bits to change... but you have to let go. So a book is never finished, it's abandoned.
I've just finished my book, having a thorough self-edit more than once.
Things I needed to sort out:
nodded occurred 53 occasions; I reduced them to 18.
smiled - 58, reduced to 24
grinned - 30, reduced to 12
sighed - only 7...!
laughed - 14, reduced to 6
just - 104 (but that included inclusion in other words, such as 'justified') - reduced to 48
down - 90 (but the same applied, with words like 'downstairs' etc) - reduced to 30
Then I did the final spell check to eliminate any oddities.
And I have just sent it off to my publisher.
Now, it's the waiting game.
(While I get on with another book, which I'm already 18,000 words into...)