If you set up an appointment for 10 minutes (e.g. 2:15 - 2:20) in the Day view you cannot see any text at all for that appointment.
Also, it would be nice if you could set up an appointment for 2:23
That happens in the real world.
In my own business, we frequently have several 10 minute appointments strung together. Your calendar day view is very difficult to read with that sort of thing. Also short appointments are awkward to edit.
Suggestion: a view that automatically adjusts itself to the time scale of the appointments entered. If the appointments are 5 minutes, scale it so 5 minute appointments are clearly legible.