It really all depends on the passage and your capabilities as a Reader.
For example, i'm not a quick reader, i read on pace, but not quick. I also need to re-read certain passages or sentences if i don't understand what they are talking about. This is because the material is boring for me.
So no matter what i had to do Search & Destroy. I was one of the lucky ones to get the easier passages where Search & Destroy worked. I pulled off a 20 on RC and i was actually surprised, i didn't think i would get anywhere near 18.
Some passages will have to be read, especially with those that have ethics questions referred to them. A lot of the exam bases your knowledge on what you know but another portion of the exam involves and little luck and timing.