Hi, Priyanka

The 1000 sets do contain good questions, but they also contain problematic questions. The problem is that the questions are a mix from lots of different sources - some of which are good and some of which aren't as good. Also, whoever typed them in didn't notice typos, at times. I've seen questions in which the given "official answer" is actually the wrong answer. I've also seen questions that had, for example, typos in the right answer for an SC - and not obvious typos but typos in a bad grammar sense. I've had students stressing about learning some rule or reading something they thought contradicted everything they knew... only to find out there was something wrong with the question itself!

In general, I believe that if you don't yet have the score you want, then you aren't done studying the problems from official sources - OG, GMATPrep, GMAT Focus. You didn't learn what you should have learned from those problems so it doesn't matter that you've "done" them already. You really haven't, because you haven't learned what you could have learned.

So, go back and start going over those again. If you also want some new questions on which to practice (that's also a good idea), I'd go with either old paper-and-pencil tests (which you can buy at www.mba.com) or questions with explanations from reputable test prep companies. The paper and pencil questions have the advantage of being real questions and the disadvantage of lacking explanations - so similar to 1000SC but without the problematic typos and unknown sources. The test prep company questions have the advantage of explanations and the disadvantage of not being official questions. Good reasons to use either - you choose! (And the same applies to CR/RC.)