Why can't I define a Trigger that is more frequent than an hour?

As of now, trigger definitions cannot be set to be more often than every hour. This is because we tried hard to find of a valid use-case that would require you to create a recurring JIRA issue more often than every hour and we couldn't come up with any. If, however, you believe you have such a use-case and you absolutely need The Scheduler to create issues more often than our imposed limit, please let us know and we'll drop that limit for you.