Earlier quoted context omitted.
I still find a number pad to be the fastest. Why am I spinning something around and trying to position it right when I just just press three buttons 9-3-0?
For alarms and clock times, my guess is data validation. The app could correct or block invalid time entries (e.g., accidentally hitting 2500), or it could restrict the entry set. It also means the number will be in the correct format. your example, 930, could mean many things (930 seconds? 9:30am or 9:30 pm?)
Who puts seconds as an input for setting their morning alarm? MAD!