More than 8 hours per day or 8 hours period?People who are high performers *on the PE exam* are removed from the pool of test takers. Doesn't mean they're all high performers on other things although some of them will be. There are test takers who are very good at test taking. I'm not one of those people but I do always manage to pass. Both types are removed from the pool of repeat takers. There are then the people who just almost made it and I think there are quite a few of them from seeing the scores people are posting. They realize it, take a review course (or take one again) and pass the 2nd time. Then there are people who are not so good at taking exams. They take it a 3rd or 4th time. If you think about it the people on the border between passing and failing who fail the first time but pass the second mean that there are people who take 3 or 4 times to pass remaining in pool. This all acts to pull down the retake pass rate.
Another reason is people take exams completely outside their university major. It seemed to be content from my last 2.5 years in university. Need to take a review course and be very serious about it if the exam is completely outside your major, this would sort of be like going back to school and seems like this is what Power exam is like for a lot of people. Although 35% of my exam was outside my education and experience I could still solve most of the questions in that area by looking at how similar problems were solved in the practice exam, having my 2 references I needed the most (I brought others but only used 2 of them and Engineering Unit Conversions by Lindeburg is key for the PE exam across disciplines), and making educated guesses.
I studied around 4 hours for this exam on plane the night before. I've never studied more than around 8 hours for an exam. I wanted to take the review but couldn't. I've spent far far far more time worrying about the results and lurking on here!