I have a few questions for which I have offered a bounty; sometimes several times. In most cases, I have done this a few times because the questions have received no answers - sometimes, no comments either.
It is hard for me to gauge the reason, sometimes. I don't know if the question is a "stumper", it's not phrased well, or no one is really interested in the topic.
Are there any suggestions as to how many times someone should offer a bounty as well as how frequently it should be done?
If you're not sure of the reason that a question is not getting answers, I'd recommend asking, either as a comment on the question (if it's fresh or active enough to be getting current views), in our chat room, or as a specific-question post here on Meta, for advice. You may thus elicit constructive criticism that could help you edit the question to attract more attention and activity from likely answerers.
That's probably a good first step before posting any bounties. I'd say that the best case for a bounty would be where the question is answerable, but is likely to take a little more expert knowledge or effort than other questions. In that case, posting the bounty could provide the little bit of added incentive necessary to spur people to make the necessary effort.
