GMAT Strategy

Guys I have time till 3rd week of october. As of now I have MGMAT and GMATPrep tests. Took 3 of MGMAT tests already and scoring around 650s. In the three tests I found around 150 600 - 800 level Quant and Verbal questions. I am off from work now so having the entire day to utilize for GMAT. Planning to study for 4 to 6 hours a day. I have already finished OG 12 and I find MGMAT questions to be bit harder compared to OG when it reaches above 700 level. I had this practice of solving 20 DS, 20 PS, 15 CR, SC and 2/3 RC passages on weekends earlier. I take 2.5 hours to solve and 3 to 4 hours to review. Instead of repeating OG problem sets. I thought of making use of the test questions taking untimed/timed tests without essays. It will come to the same pattern of 2.5 hours for solving. But reviewing Practice tests takes more time. Is it advisable to follow the above approach - repeat tests too often like 2/3 tests a week and extract as much tough questions as possible from the tests and learn/review/solve or go with the usual stuff of taking a test 10 days once finding the weak areas and solve problems/review ??? Experts please suggest.