So I'm one of those people who looks fairly smart when it comes to math and science, but my verbal reasoning skills usually indicate the abilities of a blind, highly functioning chimpanzee.
I am doing Kaplan as well. I totally committed to their strategy, and then one day I decided to try a different technique. I started out with 6/7 on VR and I am now scoring 9/10 (at least, I have on the past 3 tests I've done).
I found mapping took too much time because I would get caught up in trying to figure out the idea of "each" paragraph and then the passage as a whole and blah blah blah.
I stopped mapping completely. instead, I tried reading slightly faster and paid more attention to author keywords rather than the usual howevers, but, yet, etc. For example, I'd still note those howevers and stuff, especially if it came at the beginning or end of a paragraph, but I found that, for me, paying attention to when the author says things like "...a clear benefit over..." or "her brilliant prose indicate a woman author...." and stuff.
I guess it sort of helped me think about the overall idea better, and I was able to incorporate the author's attitude as well. Kaplan's method does work, and I found it to be a great starting point. But on the real mcat there are 7 passages, not 6. also something to think about.
Lastly, reading the passage through and noting the words I mentioned above helped keep the passage together. Mapping forced me to stop and "chop up" the passage, so I think that, for me, it interfered with my overall understanding.
Also, Kaplan is good about emphasizing outside reading. I think this did in fact help me. I'm not one who usually reads the Economist or Atlantic or New Yorker and such, but I started to and the writing style is long and boring enough that I got more used to it, which helps in VR passages.
But something that will never improve for me is: I always think I bomb VR when it ends.