The [Community process](http://meta.math.stackexchange.com/tags/community-user/info) will occasionally bump random questions without any activity triggering it. That tells me that bumping old questions is indeed desirable, as long as it doesn't affect too many in too short a time. And I'd rather see a post bumped because it got improved than just bumped with no improvement. So if you want to answer a question or improve a post, I'd say go ahead, improve our site with valuable content. If the questions you process are similar in nature (e.g. because you're going over a given tag listing, or all posts of a given author, or deliberately searching for some common misspelling or dead links or something like that), make sure to limit your bumps so that they don't come to dominate the front page. Perhaps check there is only one or two of them in the list at any given time? If, on the other hand, you don't intend to substantially improve the post, but only edit it for the sake of bumping the question, then I'd rather not see that tool being abused. If you want to draw attention, offer a bounty. Or hope for luck and wait for the Community process to bump it.