12-Months,

If you own the OG, and you own all the ManhattanGMAT materials, the chances that you need MORE gmat problems is very low.

(I have taught the GMAT for over 1000 hours, and have tutored many private students to scores over 750.)

You almost certainly need DEPTH, not BREADTH in your studying. I.e. more problems are not the answer.

Please correct me if I am wrong, but I would guess that your procedure is roughly to do a set of problems, check the answers, look at some of the wrong ones, then move on to another problem set.

You are missing some fundamental learning opportunities. I suggest that you spend roughly a 2:1 ratio of time reviewing to answering-questions. For example, if you spend 20 minutes doing a set of quant problems, you should be spending 40 minutes reviewing those problems.

I used to study in hour-long chunks of time doing 10 problems in each hour. It takes 20 minutes to complete the set and leaves 40 minutes for review. Perfect.

For each question you should ask your self:

Did I answer this question (1) correctly, (2) in sufficient time, and (3) with high confidence. You should do a deep review of all problems that do not meet ALL three criteria.

During your review assess the following:

(1) Was I able to correctly categorize this problem
(2) Do I have a concrete method for solving problems of this type?
(3) Do I have a back-up method for solving problems of this type?
(4) Do I understand the content needed to correctly answer this?
(5) Can I execute that content in sufficient time?
(6) Did I spot the "trap" answers and understand how they were derived?
(7) Have I achieved mastery of the content in this porblem?
(8) If I see this problem or a variant again, will I get it right next time?

If you are truly answering all of these questions for each problem, your score will improve rapidly and by hundreds of points. I guarantee it. (Assuming you don't have legitimate learning disabilities.)

-Tom Rose
www.TheMBAShow.com

Full Disclosure: I work for ManhattanGMAT