UMB,
if you are scoring 48-60 on math what do you need to get in verbal to get a 710??
anyway, I think Reading Comprehension might be one of the hardest things to "learn" vs. something like SC where there are formal rules to follow etc... and at least in CR you can teach yourself how to use logic
to improve your score to a certain point. I don't know if re-reading a bunch of passages would give you the biggest bang for your buck vs. using that time trying to improve your grammar radar or practicing identifying logical flaws etc.
that is just my opinion though. to me math, grammar, logic, they all have rules that can at least be memorized. going over a math problem you got wrong helps you nail the concept in your head. you know you will probably encounter a problem using a similar concept again. in an RC passage, well.. not so much. reading comprehension to me is different... you read it and you get it or you don't.
my advice would be if you think you can't improve elsewhere, reread all the RC. if you've got room to improve in SC, CR or even math, skip RC