Many campaigns occur on the same world, sometimes successive, but often time separated enough for no interaction with other campaigns. Sometimes I use a different setting. We often go back to long term, favorite settings - so the past settings don't die, just sometimes I take a break and introduce a new setting for a single campaign long or short. I enjoy setting design, and because I publish, sometimes becomes something to finish and release. I chose Yes, but my setting is homebrew (which seems a majority in the poll, so far...)