How frequently are you taking tests? For the entire length of a prep program, most people should not be taking more than 5-6 tests
total. Tests are used to measure progress since the last time you took a test, and to set priorities (based on strengths and weaknesses diagnosed by the test) for study going forward. We don't actually improve (much) just by taking a bunch of tests over and over again.
Earlier in your study, tests should be taken about once every 3-4 weeks. As you get closer to the official test, the frequency should increase to every 2 weeks and then once a week. But that "once a week" timeframe typically happens only twice: two weeks before the official test and one week before the official test. Prior to that point, tests shouldn't be taken more frequently than once every 2 weeks.
Have you also downloaded the GMATPrep tests? (
www.mba.com) These two tests, coupled with the MGMAT 6 "clean" tests, should be more than enough for everyone if you are using the tests in the most effective way. These are official questions, so GMATPrep is the best in that sense, but there are no explanations (though we've got GMATPrep folders here on the forums for you to look up explanations and post questions).
When you reset the MGMAT or GMATPrep tests, you will likely see a mix of already-seen and new questions. The number of new vs. old questions you see will depend upon the progress you have been making. If you've made a lot of progress and raised your score, you won't see as many repeats, because you will have moved yourself to a higher pool of questions. If you haven't made a lot of progress, you'll see more repeats.
And, again, it's not worth it to take a practice test if you do not feel you have made a lot of progress since the last practice test that you took. You should be able to say, "Okay, on my last practice test, I struggled with timing on problem solving questions in the Word Translations and Algebra categories, but I've done a lot of work in that area and now feel that I can answer many of those questions in an appropriate timeframe. I'm also able to recognize when I can't answer the question, and I can make an educated guess before moving on without wasting a lot of time. Now, I'm going to take a practice test to see whether I really have fixed this weakness, as I think I have." (The assessment above is just one example; you should be saying this about multiple weaknesses in order to test many things on the next practice test you take. That's why you need weeks before you take another practice test.)
You can re-take both GMATPrep and MGMAT CATs as long as you follow a few guidelines to minimize the chance of artificially inflating your score via question repeats. First, anytime you see a problem that you remember (and this means: I know the answer or I'm pretty sure I remember the answer, not just "hmm, this looks familiar..."), immediately look at the timer and make yourself sit there for the full length of time for that question type. This way, you don't artificially give yourself more time than you should have. Second, think about whether you got this problem right the last time. If you did, get it right again this time. If you didn't, get it wrong again. If you *completely honestly* think that you would get it right this time around if it were a new question (even though you got it wrong last time) because you've studied that area and improved, then get it right this time. But only if you're totally convinced you would get it right this time if it were new.
