“If you do it in practice, you’ll do it in a game.”
I don’t know who said this originally, but it’s a piece of sports wisdom that jumps right off the page at me. When I came across it recently, the person saying it meant that if you do it right in practice, you’ll do it right in the game.
But the opposite is true, too. (And of course, I’m now not thinking about football but about communication.)
If you phone it in when you practice, you won’t be dynamic when it’s time to do it for real.
If you don’t ground your speech in intention when you practice, you won’t know how when you step up to the microphone.
If you don’t do your whole presentation or speech out loud at least once in practice, something is going to pop up that you didn’t consider and throw you off.
In short, if it’s important enough to stand up in front of people and say it, it’s important enough to spend some time working out the kinks.