a couple of things:

* if you're already scoring in the 710-740 range, you may want to start shoring up the other elements of your applications. for the top schools, additional points don't really matter that much once you've moved into the mid-700s.

* when you study the OG quant problems, make sure that you're deriving takeaways from the problems. specifically, for EVERY problem, you should be able to fill in the following sentence:
if i see ______ ON ANOTHER PROBLEM, i should ______"
this is where you're going to get the big points - by making connections among different concepts.
you should try to get to the point where you're like an experienced improv actor: nothing at all is actually improvisational anymore, because "you've seen it all before". any situation you could be presented with, you could just relate it back to similar situations you've seen in the past and act similarly.
you're trying to get to the same point with gmat problems: if you amass enough TAKEAWAYS of the aforementioned type, then you'll eventually reach a point where almost every problem reminds you of several other problems you've seen in the past - and you can proceed to use the tools that worked for those problems.

just remember the following when you study:
you are never going to see these particular problems again.
do not ever forget that.
if you're spending excessive time pondering the little stupid details of the specific problem you're studying, then you're wasting your time. it's only the connections to FUTURE problems that matter.