Based on what we keep seeing in the band queue, I'd like to remind our contributors that approving band submissions solely based on one digital (one-track) single release is still the exception rather than the norm. I know that a previous news post on the matter states that one single can be acceptable in certain contexts (ex. with such unusual length that one might as well call it an EP; in addition to other criteria such as cover art and downloadability being met), however as a rule of thumb and for the overwhelming majority of cases there should be at least two before we'll even begin to review the submission for any other requirements. This particularly holds true if the band is playing a borderline genre, since multiple singles can offer a better picture than one, even if it is comparably lengthy, although moderators may opt to reject a submission even so if the available music so far remains ambiguous.
Also, there is no 5-minute rule.