For difficult material, I photoread often, as much as I feel the urge to. It works for me, as long as I do not let myself get anxious. I PR the book upside down, sideways, etc. I then wait 5 minutes ( 20 is not necessary for me, but I have had experience for a year now with this system and practice often) and then ACTIVATE.

Regarding incubation on the internet, I find it to be no different than incubating book material.

In terms of superreading the heavy material, I find it is best to learn the material in layers! Superread and on the first layer
of reading, look up trigger words and concepts that interest and intrigue you.
Then later on, while incubating, form questions and suspense in your mind about how that material you superread can be applied to your PURPOSE.
Day 2 PR again and incubate. This is the second layer. You will supperread with greater purpose and more material will make sense. Be prepared for more natural motivation to begin infusing your spirit and mind , as you are eager to activate, a little later.
Continue this process daily, and you will probably gain great mastery of the material.
This never fails for me.
I am accomplishing unbelievable tasks, these days, that I never dreamt were possible, before taking the PR course.
You may also want to check out Paul Sheele's Natural Brilliance book and the models used, to supplement what you are already doing! For me that was helpful. Good luck!