Yep
The way my brain works, I need to compartmentalize (if that's a word). I use several colors of hilighters and then circle all of the numerical values. Although I use several colors of hi lighters, I don't use them a lot. I will use one color for key words, another for key topics, etc. That way when I'm scanning the book for an answer I have some direction. An example would be the recent Tx Residential Accessiblity Specialist test I took. In the book I hilighted with one color the references to historical buildings with which I had difficulty understanding the scoping requirements, what was exempt, etc. Sure nuff, there were questions on the test that dealt with historical bldgs and I was able access the answers quickly. Passed the test too, whoop for that. I've probably taken about 40-50 code tests over the last 30 years and I've learned what works best for me. BTW, I've passed almost all of them the 1st time. The exception to that was the Houston Master Electrician test which I finally passed in March of '89 after about 5 attempts. That was a long drawn out slugfest!
Bottom line is work on a system that works for you. Devise a system of marking your books. Don't mark them too much, that can be counterproductive IMHO.
BS