We live in an age where the entire school system is antiquated, as we are no longer in an industrial revolution. Also, homework (as kids in America know it today at least) is based off an Italian punishment method.
Hence why you're drained after doing 4+ sets of it.
And yet, you're still encouraged to read (for fun) for 30 minutes, perform physical activity for 60 minutes, and get 8 hours of sleep, while doing 3.5 hours of homework per night, attending school for 7 hours, and waking up as early as 5 am to get to school on time.
And that's before extracurriculars, college prep, and a part-time job.