that depends on how many votes an article gets, doesn't it? I don't remember the formula you posted before, but doesn't an article that gets more votes stave off the decay longer?

In addition, I think that the perceived amount of stay is longer. While the front page as a whole changes faster, there are certain articles that stay for quite a while. It's less noticible if it's an article you liked, but if it was something that you hold contempt for, you'll tend to notice it every time you login.