I've been at Examiner three years now. I've never been very prolific, but I've stayed active for all but one month.
I've also made the (old) $25 payout every month, even when I only publish one article a month.
Your topic really makes a difference. I write about firearms and that topic has more potential than many of the more specialized or niche topics. I also write for a national audience, even though it's a "local" title. I learned early on that you can't "write local" and get the same kind of hits you can if you aim for a broader geographic audience. (They've eased up on the requirement to "write local" since then as well)
Most of my articles make $15 to $25. Some do vanish after only bringing in a couple bucks, but every now and then I hit something good that really earns. My article on the Guns of James Bond brought in about $125 by itself.
In 2013 I plan to try to publish a minimum of 3x a week to see if the more frequent publishing increases my readership to the point where I bring in more per article. (Obviously, I should make more if I write more, but I want to see if there's any critical mass I can reach to get more hits per article, not just more hits because I'm publishing more).