I had a conversation a few weeks ago with a guy trying to get his GRE quantitative score to 165 or higher.
He had taken the real GRE a few times, and the highest he'd gotten on quant was a 161. On Powerprep he had gotten as high as 164. When he told me what he had done to prepare, I was impressed: he had studied with a private Manhattan GRE tutor, he'd done everything in the ETS books, he'd completed most of the 5-lb. book, and more.
The first thing I realized he needed to do was review better. I told him to re-do the ETS math questions from scratch, and review each until he was sure he'd found the most efficient way to do it. I knew doing that kind of review would teach him more about the test and improve his math GRE skills. But since there are only so many ETS GRE math questions to practice with, I started thinking about where to get additional practice.
We both agreed that Manhattan questions weren't enough like the real test to be of much help at his stage. It was then that I decided to give him - and you, if you're in a similar situation - some unconventional advice:
Practice with official GMAT and official SAT questions.
Huh? you might be saying. Well, here's why. Both the GMAT's problem solving questions and the pre-2016 SAT's math questions are written in the same way as many GRE questions. They're written with a REASONING component. I've never seen any test-prep company write math questions that consistently had a reasoning or logic component built in. Why not? It's really hard to do. It's much easier to write a convoluted math question than it is to write one that involves logic, or that rewards you if you're insightful.
The GRE, the GMAT, and the SAT are all written by people - psychometricians - whose job it is to devise questions that involve reasoning. Even better, the GRE and the pre-2016 SAT are written by the same company, ETS. By practicing with the GMAT and SAT in additional to the GRE, you'll be getting used to this reasoning component (if, of course, you use official practice materials). Make sure that you're using the official GMAT guides (published by GMAC) and the official SAT guides (published by The College Board).
So how do I know this works? I haven't told a lot of students to do this yet, since not many need 165+ and are falling short. But I do have one data point: me! I've tutored the SAT and the GMAT, and many new GRE questions have reminded me of questions I've done for those other tests, and it made those new questions easier as a result.
So think about cross training for math with the GMAT and SAT if you seem to have exhausted the ETS material.