Why do meetings start on the hour? And last an hour? Because someone at Microsoft made the calendar default that way when Office was ubiquitous and no one has ever changed it.
The problem is that other people's meetings finish on the hour. You cannot be in the meeting room at the exact time that someone else finishes. So, there is a very high chance that you are going to start late. Others have back-to-back meetings all day even if you are conscientious enough to avoid them.
Why not start at 2mins past, 5mins past or 10mins past? People might actually turn up early thinking it starts on the hour. You might actually be set up to start on time.
Similarly, why finish on the hour. Knowing that your colleagues do not have the time management skills that you do, help them out by finishing at 5mins or 10mins to the hour so they can get to their next meeting. Anything you need an hour for can be done in 30-45mins anyway.
Give someone the gift of time. Make your meetings that ones that start and finish on time. Schedule.