Personally, I don't think there is anything wrong with having a repertoire as a writer. The ability to do different things leads to more flexibility, so if you're able to publish personal essays, feature articles or humor articles, the better for you. Of course, I don't think it's good to spread yourself too thin, but other freelancers firmly believe in really narrowing in on one specialty and focusing on that. There are benefits to that as well, such as being able to build more long-term relationships with clients. If you feel that you're a niche kind of writer, this site has a few ideas on how to find a niche and operate within it.