In last few years, I have seen people improving their scores by 150 points. On the other hand lot of people get stagnated at oneparticulasr score and are not able to improve despite putting countless hours. I have listed the common mistakes made by most of them.
1. Recognise flawed approach:
I have seen people practicing 5 hours a day religiously for 4 months but still getting stuck at 650-680. Obviously lack of practice is not the issue. The problem is the flawed technique you have been using all along.. So the more you practise the better you are getting at that flawed technique. Your technique is not the one meant for cracking GMAT problems. Only remedy is go back to the drawing board and analyse your technique. A correct technique will work in 100 % of cases.
2. Not taking enough tests:
GMAT will test, other than reasoning capabilities, your mental stamina. When you start taking mock tests, this is the first thing that you realise. Clearly final test day is not the day to check your stamina.
Mock tests will help you build that stamina and when you get comfortable with this aspect, should you be thinking of taking the final test. Take 6-8 mock tests before your final GMAT . Try to take them in the same time slot as your actual test.
3. Consistency is the key:
I am talking about a simple choice between using 2-3 hours every day vs leaving everything to weekends. Daily routine is the standout winner here.
GMAT is not a test of memory. It tests you on reasoning skills which take time to build. Spending 2-3 hours every day gives your mind just enough to internalise in an optimum way.