Actually, the show has had to run for at least a few series before it can start making clip shows. Seriously, a one series old show airing a clip show?
Example: Futurama lasted for four seasons, and never aired a clip show. Hell, the only clips showed from earlier episodes were from the Pilot episode. Those were purely flashbacks.
Additionally, some clip shows are actually quite entertaining, because the writers manages to reveal some new information based on past events. Not always though, sometimes the clip show is purely because of lazy writers. Like on the Simpsons. But as far as the Simpsons goes, I don't blame the writers, that show have used up every joke it could every possibly do. But I guess the show must go on...
But a "clip show" can also be an indicator whether or not the show have jumped the shark.