In a young site I participate in, the community is trying to figure out how much we want to focus on different parts of the scope, and what is and is not off topic. There's one point that has been controversial, insofar as it's a topic that has dominated the scope so far but not everyone is happy with it. It's prompted one or two meta discussions, but no clear consensus has emerged.
One user asks a lot of questions. A lot. Roughly 20% of the questions asked all-time are by him, and given that he joined late, the percentage of recent questions is far higher. He used to focus on one or two topics, one of which was the controversial topic mentioned above.
Some of his posts are good, while some are not. In the beginning, his posts were fast, furious, and not so good. Now, things have changed, and he asks better questions about a wider range of things, while still somehow maintaining his asking rate.
I'm slightly concerned that he might drift back into asking more questions about the controversial topic. I think that they'll be good questions, judging by his recent progress, but if he does so, a high percentage of questions on the site will be about that topic. It's clear that this is not good, because while it adds more content, it steers the site towards one topic and one topic only.
How can I stop this from happening? I'm not a moderator, but a regular (quite active) user. My position on the issue of the scope being slanted towards this topic is shared by others - and like I said, it's been discussed, to no real consensus - but I've never talked about the user's high question rate, nor, no my knowledge, has anyone else.