Another side note observation. I have never seen in the meetings people keeping track of when the meeting should end. They are used to round numbers like 1:00, or 14:30, but i haven't seen someone jumping up at 3:55 to go to another meeting at 4:00. It's not like everyone is constantly looking at their phones to see if the meeting should end now (unless that's a very boring meeting). So, unless a phone gives you an electric zap at 3:55 i don't see how this early ending is helpful. So, instead of having 3:00-4:00 and 4:00-5:00 meetings back to back, you will have 3:00-3:55 and 4:00-4:55 meetings in your calendar. How this will help in a busy meeting case? Unless you make gaps of 10-15 minutes and this gives you time to notice that this meeting is over, but then you are losing a lot of available meeting time.
P.S. there is a white space gap at the bottom of this article ;)