To me, this ties in with discussion about branding. Some writers plan their material in a career-focused and limited way ("I only ever publish on topics A, B, C") or a spontaneous way ("I publish whatever strikes my fancy"). There's pressure for writers to choose the former, usually under the rubric of "branding," because, supposedly, "readers want to know what to expect from you," and "your like-minded fans want to form a community," and so on. There's truth to that. But in my own reading life, I choose both kinds of writers. There are writers whose topic I can predict because they only ever write about one thing, and I think of them and go to them when I want material on that topic. There are also writers who surprise me, and I go to them to find out how they're experiencing being human today.