Hi gmatg01,
Each practice CAT test is really a 'measuring device' - when used correctly, it will give you a realistic score and help define your strengths and weaknesses, but it will NOT help you to fix any of those weaknesses. To raise your scores, you have to put in the necessary practice and repetitions. The CAT will show you whether your studies are helping you to improve or not.
Most GMAT questions can be approached in more than one way, but at their core they're all 'critical thinking' questions. One of the difficulties in just doing lots of practice questions is that "your way" of approaching the question might involve some inefficiencies that you're not aware of. Those same inefficiencies would likely impact how high you could score on your practice Exams (and on the Official GMAT). This is all meant to say that beyond just doing a lot of practice, you also need to focus on learning the Tactics, patterns and little 'secrets' to the GMAT - since the Exam is consistent and predictable, you CAN properly train to score at a high level. Investing in the proper resources can help you to raise your score and save time.
1) What is your goal score?
2) When are you planning to take the GMAT?
3) When are you planning to apply to Business School?
4) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich