IMHO: It does make for an unusual UI. Wouldn’t that also mean an odd API for others? Shouldn’t all time values be passed in the same manner? If so, can all time values be limited to 63 units?
Additionally, you will have to explain your logic to every user/coder that wants an odd variation of these units, i.e. 90 minutes. As you have told me, this is not a pleasant task to justify your logic.