I've used the INSIGHT Book Test for close to twenty years now (since it was first released) precisely due to the fact that there are multiple ways of knowing what information the participantS (yes, plural) are looking at... you can literally move from person to to person, using random pages and reveal a ton of details... it's worth every penny and then some, as far as I'm concerned.
I loathe all the "older" force a spot type systems in that most aren't appropriate to today's audience when it comes to keeping their attention without boring them (and some of those contrived methods of finding a random page, paragraph, etc. are exceptionally boring and anti-climatic).
You may look up Dr. Bill (Cushman) book THE FOURCE however, it has some thoughts for a devilish means for doing a Book Test that appears uncannily random, is flexible, and the sort of thing that any fast thinking performer can practically do impromptu. This will allow you a similar effect to what you've been doing but in a format that's far less contrived as doing a
card trick to get there... Then again, you can use any number of
Add a Number methods to gain similar cleanliness.
Bob Cassidy offers several different book tests that are worthy of study as well, if I recall it would be on the "
Mentalism of Bob Cassidy" CD (look for his Elemental & Principalia topics).
Finally, there is the simple and most elementary means of being right with any kind of book tests;
* Pocket Writing
* Swami Writing
* Simple Billet Work
* Muscle Reading (Pendulum)
The four most rudimentary skills in all of Mentalism; why get complicated?