This is something Cullen and I were actually discussing not too long ago, but it's still interesting to think about: have you ever noticed with a number of animated series, the creator(s) is/are quite involved with the writing process for the first season or two, then basically turn it all over to a writing staff afterwards? That's one thing I found intriguing about COURAGE THE COWARDLY DOG as a kid, John Dilworth wrote a bulk of the first season, but after that, wrote only two episodes during the second and final seasons (one of which was the awesome, yet infamous Mask episode).
Conversely, you have some animated shows where the creators continue writing throughout the entire run of the show, like COW AND CHICKEN or ED, EDD N EDDY... in fact, even though aka CARTOON had a writing staff, seems like almost every single episode of EEE was conceived, penned, or co-written by Danny Antonucci, then again, he has said that everything we see on the show is from his own childhood experiences, or based on the things his sons got into.