This reminds me of a "rule" I've heard from TV series writers. They operate with a dozen people locked up in a large writing room for the whole day. Their job is literally to "say one thing in the morning, and one thing in the afternoon". That's it. They don't have to say any more than that, but they better damn make sure that when they open their mouth, what they're going to say is worth the other folks' time to hear. They can always say more, but people aren't paid by the number of words they say in meetings, and in fact speaking too much can really burn someone with the other writers if they keep hogging the floor to say things that aren't the most insightful in the world.

I feel that's a useful test to use as well before talking in a meeting: is what I'm about to say something that really needs to be said here and now?