Not sure, Dio, but in the US kids leave high school with the accumulated grades from all the classes for their entire high school career. There's no big final exam like GCSEs at the end of high school. Each class you've taken for four years has a final exam and those go on your high school transcript. Depending on the school set up of daily number of classes, students can leave with 28 or so credits/grades for classes. Some high schools have 6 classes a day, some have 7, and some complete their classes in half a year with 4 classes in Fall and 4 classes in Spring for a total of 8 subjects per year. As long as you pass each of those classes, you get the high school diploma.
It's interesting, the different secondary education systems around the world.