The winner from Last Comic Standing was on Stern a couple of weeks ago and he mentioned something interesting. Doing that show, he burned through all of his material, so he had to start over trying to build up some new stuff to work on even a 6-minute set, much less 20 minutes or an hour. Comedians who write their own stuff have a tough time, no question.
But...
How much are the writers on these shows making? They are paid to write jokes and they all come up with the same front-page, cop-out humor that at best gets a good, solid Awwwwwwww. Mean-spirited, canned, freshman-quality pablum is spewed every night and these people are drawing celebrities and politicians every night for now reason but to capture the gaze of brain-dead viewers who are too lazy to change the channel.
Even Bill Maher-- who I think is basically full of crap 90% of the time-- goes for the obvious, and he only has to do a bit on Friday nights on a show where he can say whatever the hell he wants. Conan sometimes gets a good riff going, but he's usually just as bad.
The fact is this. The Daily Show is where it is for a reason. All hale Jon Stewart and the fake news reporters and writers on that show. And Tough Crowd, but that's another story.