I think the majority of schools have two ways for students to get through schools.
One would be to skirt the system, prepare for exams, and basically retain hardly anything.(This happens extremely often now, especially because of the number of smart yet not-so-determined kids who can get away with coasting, but they don't realize that it'll cost them later.
American schools tend to be lenient on the amount of time required to be spent on school work which allows them leeway to pursue things interesting projects if they are so motivated.
The second is to actually learn the material and work your way through it, thus being able to handle the exams well, and getting something out of your education.
The large part of why students pick the first option is most of the time the material is not very challenging and students find it much easier to slack off than take an initiative to go above and beyond the standard curricula.
The flipside occurs in Asian schools, where while the material is not challenging, it does take a lot of time and effort (not mental, but just constant work) to do well, and survive. This albeit crushes the innovative side that students should nurture at a high school level.