>Tests effectively do nothing except test the tester. That's my controversial statement for the day!
We now have SATs at 7 and 11. They just give a range (eg level 2 by age7, level 4 by age 11) and seem to have little use for the children. In England (but not yet in Scotland) they are published in the press and their main use seems to be in ranking primary scools in order of the proportion of children reaching the expected standard for their age. If doesn't give any information about the number of children exceeding the standard, so schools are encouraged to focus on borderline pupils - this may or may not be a good thing, depending on the education standard of your child. Although there is support for low achievers, very few schools have support for high achievers who can become bored and disruptive. In most cases the results can be predicted from the relative wealth of the postcode area (zipcode). In many cases schools are offering a great deal to children with little home support but the praise tends to be short-lived, in some cases schools in "good areas" realise that they have to improve. Either way, the flow is still to better areas for those who want to give their children a good start and the published tables only help this process.
At seconday level, often one school from 11-18 but with variations around the country, we have tests at 16(ish) and 18(ish). At the top end of the school many pupils will take up to eight or nine GCSE exams at 16 and three "A" levels at 18. In Scotland it is different with up to eight or nine "standard grades" at 15/16 and five "highers" at 17/18, followed by an optional extra year with increasing specialisation or an opportunity to add more "highers".
I think we all regard the system as good or bad, according to out own level of success. I found the courses interesting and the syllabus wide enough for the teachers not only be teaching for the exam. The exams were often in three parts with MCQs, essay questions and then practicals/orals/aurals for sciences or languages.
I often cross swords with teachers, especially a couple who were not very bright (I was much more aggressive in those days, mild and gentle soul that I am), so in those subjects I appreciated the external markers who made sure that everything was fair. I'm a fairly lazy person, willing to dot he minimum, so I'm sure that I would have worked less hard at school or university without the thought of an impending exam!