[dba-Tech] Outlook Calendar's time slot options

You can change the Calendar view's default time slot from 30 minutes to one 
of several other options by right-clicking the Calendar view, choosing Other 
Settings and choosing an option from the Time Scale control.

The list of possibilities is odd. First, it's rather short. Second, why 
would 6 minutes be more universal than say, 20 or 45 minutes?

As far as I can tell, we're limited to only those options -- can't find a 
way to add an item to this list.  Does anyone know if that's possible?

Susan H.