I took the GMAT a few months ago and got a 675 (Quant: 84 [96th percentile], Verbal: 87 [99th percentile], DI: 79 [78th percentile]). For context, I am a recent graduate from undergrad and applied to deferred admissions programs in my senior spring with a full time job in investment banking secured but I know in the long run an MBA is in the cards and so felt like applying now would be best for me. My first tests were really terrible. For some reason I expected the GMAT to come easy considering I did pretty well on the SAT (1500+) and being used to the testing environment as a college student. However, in my first diagnostic test I took in early January I got a 475. Over the next few week I grinded
Target Test Prep which has been extremely impactful in my increase in score. TTP allowed me to review concepts that I hadn't learned in the past few years as well as taught me new ones that showed up on the GMAT. Additionally, what was most helpful is the sheer amount of questions on TTP. There are so many practice questions on every topic to truly master each concept. Overall, I took 4 more of the GMAT Focus official practice tests from online and saw marginal increases to my score like 545, 575, 615, 645. Considering I hadn't gotten over 650 I expected to do pretty okay around the low 600s on the test but managed a 675.
I will say in terms of studying the GMAT is not something that you can score on just from your intelligence (for me at least). It definitely takes practice and getting used to the types of questions. Additionally to get through the entire TTP study lesson plan it required a lot of time. I studied for 3 months with 2-4 hours of studying a day and barely managed to finish the lesson plan. Overall I am very happy with the results!