My high school went from a val/sal system to a "distinguished senior scholar" of the top 1% (500ish graduates each year) about 5 years after I graduated. One of the reasons (so I hear), was because there were students who would take 6-8 academic classes, mix of AP (5.0) and standard (4.0) classes - however there would also be students who only took 4-6 academic classes + 2 "non-graded" classes (such as cheer leading, monitor, study hall, etc). Those only taking 4ish academic classes (in AP classes) would end up with higher GPAs, even though they took fewer academic classes. I tended to think that they just new the system and worked it - but there were finally a bunch of helicopter parents with influence who changed the system
While looking at the course schedule for information for my kids, I see that each student is only allowed to take 1 non-graded class now. Probably a better idea.