Another example of confusing numeric systems emerges from 12-hour clocks. For many people, asking them to specify which one is 12AM and which one is 12PM is likely to cause confusion. This confusion is immediately cleared up if you just adopt a 24-hour clock. This is a hill I'm willing to die on.
But I do wished people would stop writing schedules in the 12 hour system. You get weird stuff like bold means PM etc. to compensate for the space inefficiency of 12 hour system