Agree with Chris above, hourly scheduling is a must for a station wanting to play, for example, news on the hour or huge top of the hour jingle.
While you're at it, could there also be options for 2-hourly, 3-hourly, 4 hourly and 6-hourly?
It sounds like overkill, but I've had several situations where I've wanted to use it, e.g. to play a weather report every 2 hours and a news bulletin every 4 hours.
Even shorter intervals would be useful in ad scheduling - then we could tell clients when their spots will play.
The one hour option is a total imperitive though.