Earlier in my teaching career, you couldn't shut me up. I equated talking with teaching. I was not really focused on my main role, which is facilitating learning.
As my career has progressed, I do far less talking. When addressing the whole class, I use as few words as possible — because I do not want to use them up. There is a real limit to the amount of information students absorb from extended teacher monologues. (I am not limiting conversations with individuals or small groups — that is different.)
"If you don't ration your intervention, what you say evaporates." — Alex Ferguson
I also make sure I save my words for VITPs — Very Important Teaching Points. It is very easy to waste them on housekeeping and homework instructions.
The other thing I have started doing is letting classes know how long I am going to speak for. If I tell a class I am only going to talk for two minutes, they are much more likely to hold their attention for that long. It also helps me avoid one of the classic behaviour management pitfalls: expecting pupils to listen for too long.
Thanks for your three minutes.