Yeah, with different tests it may be different. But in the UK the government pushes for 'more challenging tests', which means more stuff to memorise, a lot of the stuff is very specific (in science GCSE and A-levels there's specific phrases you need to use to get marks. Accurate descriptions which don't include those key phrases don't get marks), and there's a lot riding on getting near perfect marks. Someone who has a good memory and a few months to prepare and an expert on the topic with years of experience (but no specific preparation) have about the same chance with these exams.