>>212611807 (OP)They prioritized keeping the writers interested enough to try over keeping any kind of consistensy in tone, canon or characterization. Roger in S1 is nothing like Roger in S5, who is still pretty different from Roger now. Same for Klaus, Hailey, Francine and most of the main cast. Even the extended cast pre-TBS era versus early TBS versus now are pretty different.
So basically they stayed funny by slowly turning into a multiple completely different shows as the years went on.