I have had a lot of my higher-scoring students tell me that they think GMATPrep is easier than the real thing. I think this is because the question pool for GMATPrep is pretty shallow (that is, there aren't that many questions), so if you score very well, you essentially use up your high-level question pool and the test then feels easier than the real thing b/c the real thing will have TONS of really hard stuff to keep throwing at you.
Also, re: the "it doesn't help you to take a lot more time" issue - academic, scientifically valid studies have been done to show that, on average, the more time you spend about about 2min40sec, the less likely you are to get something right. Plus, that extra time has to come from somewhere, and typically it causes people to make careless mistakes on lower-level problems they should have gotten right but didn't because they were rushing.
Remember that, on the real thing, the questions are all written such that someone can do them in 2 min. Maybe not you, but someone. If you feel like you need 4 min to do such a problem, that's actually an indication that you don't really know how to do it b/c you can't do it in the expected 2 min timeframe.
Particularly on the math, you have to remember that, no matter how good you are, the test will give you stuff you cannot do in 2 minutes, and it will also give you stuff you cannot do at all (without, say, a textbook or an instructor sitting next to you
). If you get sucked into spending too much time on these kinds of problems, you will have a double whammy - you'll be more likely to get that problem wrong, plus you'll likely cost yourself points elsewhere by having to rush.I agree that some of our quant questions are too computation-intensive. We actually have an analysis algorithm we run on our own test questions as we get enough data points from students, and we are going back in and altering or dropping questions that take too long, are too easy or too hard, that aren't properly discriminating (that is, people with lower scores should be more likely to get a particular question wrong and people with higher scores should be more likely to get it right), etc.
