It's pointless. I'm gonna be parroting things people across the internet already say but it doesn't make it any less true, when you study to a test you're testing your ability to memorise, not your intelligence. I don't remember a single thing I learned in my last few years of Maths at school, but my B grade in my GCSE implies I do. And if you didn't manage to memorise the information you needed, you got below a C, which by no means is a measure of your ability today. There's not a single question in my GCSE exam I've applied to my life in any way since finishing school. NONE.
Not to mention, you're taking kids whose brains haven't even fully formed yet and who know absolutely nothing about the world, and telling them that the rest of their life depends on getting high scores in these exams, and therefore they need to spend their lives up until that vague date years and years into their future dedicating themselves to things they're being told in a place they don't want to go to but are forced to go to every day full of rude adults who make them feel like lesser people. Of course they're not going to do that, they're going to rebel against the system that forces them into that lifestyle however they can, and when it comes time for the final exams they still have no idea what's even banking on their results. And even though they have at least 40-50 years ahead of them after those exams are completed, in which they go out into the real world and actually develop real skills and see why they needed to do well in those exams, those results will be held against them for the rest of their lives as a measure of their intelligence. It's ridiculous. Shit needs to be reformed.