Weird, L4D2 hasn't been updated since 12/18/09. I just verified now (1/3/2010) and im AMAZED that they didn't update every 3 hours like you said.
Ok yeah, I figure you weren't being literal, and like I said before I understand they (steam) updated often, but still.
"They have a business to run," as you stated is accurate. That business is based upon the service of providing up-to-date trainers. If those trainers are not provided, why should I stay? Do you understand that?
Yes, the three hours thing was hyperbole.
However, trainers are very much NOT the whole of CheatHappens' business operation. Left 4 Dead 2 is not the only game out there. So many other, newer, more popular games need trainers too.
Like I said, they have to work on other trainers, play the games for those trainers, review author submissions, manage UNL accounts, and keep the site running smoothly. They also have personal lives, families, children, and all that.
It would be a bad business model to focus on one game. Instead of making five trainers for one game, why not make one trainer each for five different games and broaden the spectrum of games you support. It appeals to a wider audience and brings in more people. I guarantee that if you combine the number of people that like Borderlands, Dragon Age, Saboteur, Modern Warfare 2, etc., it will far outweigh the people that like L4D2. I'm sure they mean nothing personal by not updating this trainer every time there's an update. It's just business.