If you're having difficulty using the system on educational material you haven't taken time to learn the system first.
It's important to have a purpose. Having done distant education prior to learning PhotoReading and knowing how to apply PhotoReading and having studied after learning PhotoReading I can assure you there is a significant difference. I save more time and have a deeper understanding of what I studies.
If you're rushing and as you said you have only tried it, you haven't actually learned PhotoReading. I recommend you do the course as instructed while listening.
Once you learned on material not relating to your studies it's still important to have a purpose for the material you are studying.
Alex