Even with shorthand or fragments of jokes, you can't go through 500 to 600 ideas in an hour. You simply CANNOT discuss ten jokes per minute, six seconds per joke. After all, if you do come up with a good joke, or even the potential for an idea, it takes time to write the lines down. It took me about ten seconds to type that last sentence. If the joke isn't written down clearly, or typed onto a computer, how will we remember it tomorrow?
It's clear, Jay was inflating everything he told Terry Gross in the interview. Even an insomniac gets SOME sleep. I'd bet you a steak dinner, Jay is not at the studios at 8:30am either. You simply can't write jokes till 3am, then be up, showered, shaved, drink some coffee and be back at the studios, with Los Angeles traffic, at 8:30am. Unless he's totally ignoring his wife, he HAS to spend some time at home. An insomniac still catches up on sleep somewhere along the line. Maybe you're not averaging eight hours a night. But surely you're in bed more than four hours a night, even if you're only sleeping part of the time. How else could a 60 year old man function?
The reason I am analyzing these statements is because Leno's need to hyper-inflate his work process is part of his mania. He WANTS us to believe he's working so much harder than everyone else because he thinks it will give him an advantage on everyone else. As a TV viewer, I really shouldn't be told comedy is such hard work. It's supposed to be FUN. Carson and Letterman tried/try to make us think they really haven't seen the monologue or other bits, so if they bomb, they can join us in laughing at how bad they are.
Modest people UNDER-estimate their work process. They don't need to tell us they're awake 20 hours a day and working most of those hours, to deliver a ten minute monologue, produced with the help of 16 other writers.