Whenever I first finish a manuscript, I like to do a read through as fast as I possibly can before I jump into revisions.
Benefits of the speedread:
1. Gives overall impressions and feel of the book
2. Allows me to focus big picture before getting down to the minutia
3. Helps me step outside of author-mode and simply enjoy
If you are revising, give it a try sometime and tell me what you think!