I work in a school in a low-achieving area.
I tell all my classes that I value effort over achievement. It's no use to me if a child capable of a grade 7 achieves a 6 because they put little/ no effort into their work, while I will always have more time and respect for the student targeted a grade 3 who does their utmost but still only gets a 2.
High-achieving students in top sets come in 4 flavours:
-works hard, achieves well - around 20-25%
-works hard, doesn't achieve - around 10-15%
-doesn't work hard, doesn't achieve well - around 10-15%
-doesn't work hard, achieves well but could do better with effort - around half the class, if not most.
Schools do an awful lot to push those students. Afternoon intervention runs most of Y11, sometimes even Saturdays and holidays. The former, even if compulsory, will have some students skipping/ having other things to do, the latter are barely attended. Homework - I'd say even in my top set, 20% regularly don't complete it. I set different revision techniques as homework throughout KS4. I still get a number of students not attempting the given technique, saying it doesn't work for them and they made notes/ did a poster/ made whatever is low effort instead.
We analyse exams and exam results with classes, go over exam techniques, review grade boundaries, give resources/ links/ QR codes for revision, literally give lessons on how to revise effectively. But as the saying goes, you can lead a horse to water...
Schools do enough. More than enough, and certainly far more than I've ever had when I was a student. Parents should do more, including ensuring their children go to bed at a reasonable time and eat decent food, let alone check homework/ address behaviour in class. Responsibility also needs to be back with children rather than almost solely on the teacher (I've had many a child tell me it's MY responsibility to MAKE them achieve). Then we might see change.
Oh, and of course that still doesn't stop grade boundaries being determined by % of students who achieved a certain mark.