You ask if PR can guarantee 100% comprehension?!
First does 100% comprehension mean the ability to get 100% on any test on the material?!
Does 100% comprehension mean to be able to get outside of the box and use this material
in new and creative ways that the original author never any considered?!
The answer would depend on how much work you put into the activation stage. Activation could actually require heavy duty SQ3R for science and math materials.
All I can say is when I was a student, I aced exams with perfect scores that most people could not even pass. I was a hard working student and most would have said I comprehended the material 100% at the time.

As an older man, I have revisited old subject matter that I mastered and have PRed it. I feel my level of comprehension is higher than ever, as I can take the material way outside the box.

Personally, I am not bold enough to ever say I comprehend anything 100%. All I can say is with PR, my comprehension is higher than ever before and I believe it is applicable to ALL academic material. The key is how you choose to activate the different materials.

Also I agree with many other experienced PRers on this thread who state that there are more important objectives than getting that 100% on the exam!

I recommend that you reread the entire thread, and really think about what has been said here. I think this particular thread is fantastic and chock full of information to give anyone an edge in academic or personal studies. In fact I feel guilty that I can get all this information for free--SERIOUSLY-- many people go to high priced tutorial sessions and will not get half the keys on how to learn, as this particular thread is revealing.

I have great gratitude for this discussion forum!