I have to confess, I'm a sporadic tweeter. Some days I'll be on twitter regularly, reading all your tweets, and tweeting a bit on my own. Some days I'll just follow a few people. Most days, to be perfectly honest, I just can't be bothered.
It's easier to admit this behavior because it's quite obvious at this point that many people are occasional tweeters. You see it all the time, a sudden spurt of 5 or 10 tweets in a day, then for a week, nothing.
Or then there are the occasional tweeters, who put up a tweet every week or two. I'd ask what the point of that is, but actually, those are people I probably will never un-follow, since they are no trouble.
In fact, I don't see myself changing my habits any time soon. When I am on twitter, it's on days when I don't have a lot to do, and it's nice to see what the latest geek-speak is.
The true mystery is that even when I've been off for a couple of weeks, I don't get that feeling like I "missed" something important and can't follow the new conversation. On the other hand, I feel like when I am reading the tweets, I am getting information I needed. Truly mysterious.
I suppose it's no different than what Yossi Vardi discovered with ICQ: being in communication is a basic human need. Wherever the conversation is, it brings us human value to be part of it. Apparently, the business value is secondary, and comes mainly as part of the "being in communication" rather than some specific tweets that you just can't miss.