There should be some threshold reached to warrant a new release. One tweak of the UI or a new color in one text box is not enough. In addition, just because it has been a few months without a release, some small fix should not be the only item to release.

Release when it is time, when all is tested, and within reason for the user of the product. Moreover, if there is no significant thing to release, do not do it just because of time passed.