The fatigue is probably a getting used to the new approach symptom. There is no reason why you only have to take a 5 minute break. See the 5 day test from the PhotoReading book. I think one thing you are noticing is that you are staying with the book for the duration. Many people will find reading fatigues them and their mind wanders off.
One of the other things about the fatigue you may need to adjust your speed. You may be going too slow or you may need to speed up. Try also doing 10 minute activation passes with a 2 minute break (mind mapping) and notice your experience.
Also be prepared for the fatigue immediately after PhotoReading. You may need to leave a longer break after PhotoReading and postviewing than you are.
Alex
