The things you say have a life of their own.
They do not fade once you are done saying them. They keep floating, and those who have heard them carry them around for an indefinite amount of time. They change in meaning. They change in strength. They change in effect.
Often they are still there once we have forgotten them. They might even become drivers for actions we later fail to understand. To our own misery.
The act of saying is anything but final. It’s a step in a process of reciprocal understanding, and we rarely do a good job with our own part.
Despite the fact we have never used it more, communication is fragile. Starting from the assumption it is not going to work is an easy way to become better at it.