I studied for the GMAT for a year before taking my first official exam. I spent the first ten months reviewing Manhattan GMAT's two Foundation supplements and eight Strategy guides. I did every problem in these books and in all three official GMAC guides. In addition, I spent time re-learning grammar (always good to know). I spent 1-2 hours a day on this material.
I spent the last two months taking the six Manhattan GMAT exams as well as the two free official GMAC practice exams. Sometime during the content learning stage, I took the official diagnostic exam. I was scoring above average on all but one category. I never actually took a full practice exam from start to finish. One day I would do the essays and math sections of the exam and then do verbal practice and review. The next day I would do 1-2 hours of math problems and then take the verbal exam. After completely finishing the exam, I would review all the problems, an effort taking several hours.
My first practice exam was horrible -- 9th percentile or so -- because I didn't finish on time. That was an extremely important lesson to always finish the exam. My other CAT exam scores ranged from 650 to 740, but most were above 700. My official practice exam results were in the high 600s and low 700s. On the official exam, I got a 650; I scored very high on each section except for math. I thought I had done pretty well on math timing and that I was dropping the hard problems. Further, I thought my math score was a fluke, so I quickly decided to sign up for a second official exam the next month. However, I decided to use another math strategy. Since I had often spent more time on the first half of the math section and rushed the last third but had done well during those practice exams, I thought I would stick to this other approach that I was more used to. My study strategy was to buy the recently released 13th edition of the official guide and complete all 800 practice questions. This took a lot of time.
In addition to this, I completed the Manhattan GMAT Advanced Quant guide. I took two official exams again, achieving the same results as before. On the actual exam, my scored dropped. My math score was identical. I quickly reasoned that I must have been fooling my self somewhere and that I would need help to identify and fix the problem(s). So the first thing I did when I got back home was set up a 20-minute appointment with a tutor. I'm glad I did and I'm glad that my request made its way to Liz Moliski. I just wished I had worked with her sooner.
Liz realized that I was studying too much and did not have a real timing strategy for math. Important for my confidence, she repeatedly told me that I was good at math. She advised me to study fewer hours and practice timing sets. The "watertight" timing set strategy is laid out in Manhattan GMAT Roadmap (Guide 0). Two to three times a week, I did 15 tough math problems in 30 minutes, making sure I was sticking to the 5 problems/10 minutes intervals. The point of this exercise was to learn to drop problems that I couldn't do quickly. This was also a way to practice guessing, which I was not good at. Once I got the timing down, the next step was to make sure that I focused on correctly solving the easy and medium problems and quickly dropping the hard problems that I probably could not do within two and a half minutes. I stayed warm on the verbal by doing a couple sets of 12 hard problems each week. I took two GMAT Focus quant exams and took one official practice test, which I did from start to finish. A few weeks before taking the third official exam, I began to make flashcards (about 40 in total by the end) using the example from Roadmap of problem types that appear often or had a useful "trick" -- an insight that unlocked the problem. I wish I had done this earlier.
The week and day before the exam, I didn't over study. I did spend several hours the day before reviewing my flash cards and some problems, but I made sure I didn't study in the evening. On test day, I got over 700!