There's really never a good reason to take practice tests more then once a week.
CAT exams are really good for (a) figuring out where you're scoring right now, (b) practicing stamina*, and (c) analyzing your strengths and weaknesses. The actual act of just taking the exam is NOT so useful for improving. It's what you do with the test results / between tests that helps you to improve.
*But more than once a week just tires you out without making anything appreciably better.
For RC, I've linked to some resources below. I have to tell you that RC is one of the slowest area to improve if the particular problem is the reading itself. You can't really rush or cram anything when you're trying to improve your reading comprehension - so just be aware that you may need more than 3 weeks, or you may need to decide that RC is a weakness and you'll do what you can in 3 weeks, but then that's it.
http://www.manhattangmat.com/blog/index ... p-passage/http://www.beatthegmat.com/mba/2010/07/ ... rc-passagehttp://www.manhattangmat.com/blog/index ... rehension/http://www.manhattangmat.com/blog/index ... n-problem/http://www.manhattangmat.com/blog/index ... g-problem/http://www.manhattangmat.com/articles/a ... estion.cfmRe: SC, try this exercise. Go back into old OG problems that you've already done. Cover up the question stem. Compare the answers and try to uncover EVERY grammar or meaning issue that's being tested, just based upon the differences that you see. Then check to see how close you got. If you missed anything, or if you thought a difference signaled one kind of issue when it was really signaling another, go back and study that difference again - what is it, how does it work, how am I going to remember next time that this type of difference = this type of grammar rule or meaning issue?
Also notice that for RC and CR, a lot of what you're telling me is: I'm going a bit too quickly and not following the process, so then I make a mistake. And then you say "But I go back after and I can do it just fine!"
Of course you can! You don't have the same time pressure afterwards! It doesn't count anymore, even if you're timing yourself (because you're not going to get a score at the end). You're letting the time pressure cause you to loosen your process. That's a bad idea. Far better to say, "When I see what I think is a really hard question, I'm going to guess quickly and move on. I'll do this a few times throughout the test and then I'll have plenty of time on all of the rest without having to pressure myself to move so quickly."
You can do that as long as you aren't going for a 95th+ percentile score on verbal. :)
So note that a lot of this really is about process so, no, don't just go do a bunch of tests or a million new practice problems, not if you're going to keep doing them with your same old process. Change the process. Then practice it on new questions or tests.
Here's your CR process:
http://www.manhattangmat.com/blog/index ... g-problem/And SC:
http://www.beatthegmat.com/mba/2010/06/ ... on-problemFor SC, you might also want to go onto our blog and read some of my posts over the past 6 months about meaning and other issues in SC.
For some quant practice, you might want to try GMAT Focus (
www.gmatfocus.com). You aren't guaranteed 700+ questions - you're only guaranteed whatever you earn, since that produce will adapt to your level. But you should be practicing at whatever your level is anyway, so that's fine.