Matt Stone and Trey Parker write, animate, and air a full South Park episode in six days. They've done this for 25 years while Family Guy takes nine months per episode. The speed comes from rapid pitching, same-day voice work, and jokes written during production.
South Park has been around for 25 years. It's basically two guys, Matt and Trey. They come up with an entire 30-minute episode in 6 days from idea to it being live. And they do that every single season and they've done for 25 years, which is unheard of.
Family Guy is 9 months. That's like normal. 6 days just breaks your brain of how do you do that? And the way they do that is they're like, Monday we're pitching ideas and then we grab the idea. The animators start drawing. We go into the studio, we start doing the voices so that the animators have the dialogue. We're working out the jokes as we go.