The entire process takes 6 months (literally) because of how they go about animating the episodes. The shows are mostly drawn by hand. South park however uses computers which, in turn, allows them to do everything in 5 days. So what the Simpsons does is they prepare a whole season 6-8 months ahead of time.
Horsepower (hp) is unit of measurement of power, the rate at which work is done. The most common conversion factor, especially for electrical power, is 1 hp = 746 watts. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses.