Being a computer programmer for over 30 years, I have had to use the 24 hour format on the computer. Living in the USA, I have had to use the 12 hour AM and PM format. Since I work with both, I know, for example, that 17:00 is 5:00 PM.
To the average person in the USA, the clock is a 12 hour format unless they are in the USA Military. The USA military uses the 24 hour format. We are all talking about the same thing. There are 24 hours in a day.
Being an outdoor sports enthusiast, I have had to learn other terms for the same things. My rockclimbing shoes and my bicycling shoes are in metric as they are made in Europe. My everyday walk around town shoes are in USA sizes.
I try to get in a 12 mile ride (20 kilometers) during the winter whenever the temperature is 35 F (1.5 C) sunny and very little breeze. I do this as once spring gets here, we bicyclists try to get in a metric century - 62.5 miles or 100 kilometers.
All of the above are different terminologys for measuring the exact same thing!
I have been wanting to applaud Canada and my friends on the other side of the ocean. While, I was going to school and only learning English, you were going to school and learned English along with your own language. I wish that our school system would have atleast had us learn French as Canada is on the other side of Lake Erie.
Hopefully, I have not bored you. I just wanted to make a comment on the Time issue in Offtopic where it belongs.
Marty