No, we should fire the people who design the curricula, and design better ones.
It doesn't follow from the fact that we're imparting only two useful years worth of knowledge in (say) 4 years of high school that students are only capable of benefiting from 2 years of high school.
It doesn't follow from the fact that we're imparting only two useful years worth of knowledge in (say) 4 years of high school that students are only capable of benefiting from 2 years of high school.