Experience becomes the best teacher in that. However if you are looking for something specific in a book and you pose the question in your mind prior to photoreading the book, with experience you will recognise the signal to stop and go back and read a section. and have your answer.
I did this with a dos programming book I needed to know some specific how to. To by pass a corrupt windows operating system to get to my data. I spent 3 minutes with the book found the answers and accessed my data within 10 minutes. It took longer to move it than it did to learn how to move it.
Photoreading adds to the regular reading skills. You lose nothing but gain a lot.
Alex
