I've been studying for the GMAT for a couple of weeks now, using mainly hard copy material (Kaplan Premier book) and short online quizzes. My test date is about 10 days from now.
Two days ago, I decided to test my actual full test capabilities for the first time, and to get the best starting point picture, I downloaded the GMATPrep and did the first test.
To my surprise, I scored 750 (so I naturally concluded that by the time I'm done studying, Harvard and Wharton will be flying their best people over to persuade me to choose them as my school

).
The following two days, I tried two CATs from the Kaplan CD - the results were horrible (620 and 640 respectively). Not only that, but I also found myself running out of time in almost every section (as opposed to the GMATPrep exam, where I managed to finish Quantitative with over 1 minute left, and Verbal with almost 7 minutes left). So now I'm thinking Harvard and Wharton will not be flying over after all, and that community colleges will be turning me down.
The above caught me by surprise, since if anything, I would have expected the GMATPrep to simulate the actual test more accurately, and therefore be tougher.
Does anyone have any insights as to this discrepancy?
Thanks in advance for your assistance.