When I define a new alarm, or change a old one, I can notice some inconsistencies. In the Alarm tab I can fill directly "At date / time" -> "in the time" field something like this 0500 that translates in 05:00. For me is Ok. When I try to do the same in the Recurrence tab -> "Recur every" field it fails (example: 0200 (it should translate in 02:00))
This is different deliberately. A time of day can be entered as hours:minutes or, to make things easier, hhmm (4 digits). A length of time must be entered as hours:minutes. If a simple number was allowed, it wouldn't be clear whether the user might have intended to enter a number of minutes rather than hhmm, so the colon is mandatory to remove ambiguity. I know that the reason for the difference may not be obvious to the user, but I think that it's better than making it ambiguous.