I passed the GAMSAT with little revision, entirely fluke I assure you. It was because I haven't done any Physics since yr 9, so I got all worked up about trying to do GCSE and A Level Physics learning in ver few weeks, that I only really had time to read through my old biology and chem notes. I certainly found that most of what you need to answer the question will be in the question and with logic. The problem is that the questions are worded so awkwardly, that by reading the question you just confuse yourself on what you already know, however, we haven't gottent his far without having it drummed into us to 'READ THE QUESTION!!!', so it's up to you really. It's not that* hard, but it is confusing. Don't forget your comprehension and essay writing as the science and maths is only a third. Griffiths GAMSAT review was indeed a lifesaver, especially his tips on how to approach and structure your essays. Good luck.