I think they know much better than us how to access different parts of their mind, and that what are the signs that indicates that they've accessed them.
Plus they know more about how to recall the information, which is a crucial part too.
Maybe they experienced things during the photoreading or any other speed reading processes that not even they can describe in words because those things must be experienced by those who would like to learn these techniques.
What I think is that consistency and not giving-up is key. For example what would happen if You would make a decision that You will photoread and activate 1 book every day in the next 90 days? Would You be better at the photoreading process? Would You read faster? I am sure You would!
Best Wishes,
Matt