I really believe that the amount of focus is not what is important. If you are diverging your eyes then you are taking the focus off the page which will allow you to relax and not try to read the page. If you are photoreading then you do not want to actually read the content of the pages.
If your eyes were diverged to the point where you saw three perfect pages, that would mean each of your eyes line of sight was right through the center of page, which would be ideal for your periphery.