The questions sometimes look surprisingly straightforward... until you fall into a trap. Once people study them and see the explanations, then they think, "Oh, these are easy!" But they're really not. The test writers are just really good at writing deceptively simple but really quite tricky questions.
Now, if someone goes into the test and scores a 51 (99th percentile) on Quant, well yes, that person is going to think that the vast majority of the OG questions are easy. And they would be, for that person, although there are still some questions in the books that are 99th percentile levels. But that person's going to look at a 90th percentile question and say "hey, that's easy!" But that's exactly what a "700+" level question is - 90th percentile.
So, in a nutshell... it all depends on your perspective. Remember that all of the 99th percentile testers out there did study from the OG, too - those are the only real questions in the game - so they must work!
The real distinction? How deeply you study / pick apart the problems. Do you ask yourselves these kinds of questions when reviewing problems?
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