We always suggest using a book that you've not read before and would like to read. It's too easy to discredit your experience if you have already read the book. When you see the results you get on a book you've never done before it's a stronger experience and motivation to improve the system.
Later review the book you've done before. Just turn the book upside down when you PhotoRead it the highlighting won't draw you in as easily as it will when it's right side up.
Alex
