You've quoted my first comment, but don't seem to have heard it. You don't practice the system, you use it. The concept of practice has a belief associated with it. Namely, that you can not currently do it, whatever it is.
If you've learned all of the steps in the PWMS then you can do it. So do it. The more you do it, the better your results will become.
As for previewing or postviewing and PRing a book. That will take you 5 to 10 minutes per book. If you can't find ten minutes, well... Maybe 100 minutes may be difficult to find. This is the good, better, best idea. Just because you can't approach the material from the best (the recommended) practice, doesn't mean you can't approach it.
I believe the also suggest activiating at least one book a day with that formula. Make the room for at most a 20 minute session a day for the activation. If that mean 2 less books to preview and PR, so be it.
If you are previewing and PRing, why not try it on a few chapters of a text book. You can leave the more scary part (activation) for less threatening material. I suspect that you'll gain a lot of benefit for your studies by doing this.
You can do it. It just one of your choices. Where are you going to decide to send your energy?
You are perfection.
Iam2 
