Lately I am doing about two a month. Just don't seem to have time for more although I have been maintaining notes for several future hubs. I do, however, regularly check questions (such as this one), review the forums and add my own posts when I have something useful to say, and respond to comments in my hubs. I also make routine updates to hubs in cases where I see fit. I think all this helps keep the Hubber Score up there.