The arithmetic nobody does
Six people, one hour. That is not one hour. That is six hours of human life, and it happens every week, and almost nobody treats it as a real cost.
If a meeting has six people in it, it needs to produce more than six hours of value or it was a net loss. That sounds harsh. It is just arithmetic.
Four conditions
One: a decision, not a topic. "Discuss the roadmap" is a topic. "Decide whether we ship the export feature in March or April" is a decision. If you cannot write the decision in the title, you probably want a document, not a meeting.
Two: an owner and a prepared room. The person who called the meeting sends the context at least four hours ahead. If people arrive without having read it, you have converted a decision meeting into a very expensive reading session.
Three: the right six people. Every extra person costs an hour and dilutes the decision. Invite the people who will be affected and the people who know something. If you are inviting someone "so they are aware", send them the notes instead. They will be delighted.
Four: an ending with names in it. Every meeting ends with the last five minutes spent out loud on: what we decided, what we explicitly did not decide, who owns what, and by when. Not in someone's head — out loud, in the room, so that three people can correct it before it becomes a misunderstanding.
The one habit that fixes most of it
Start on time. Every time. Not "once everyone is here".
This sounds like a small disciplinary thing, but it is the highest-leverage habit in meeting culture. When a meeting reliably starts on time, people arrive on time, and when people arrive on time the meeting gets shorter, and when it gets shorter the agenda gets sharper, because you cannot fit vagueness into twenty-five minutes.
Late starts are not a punctuality problem. They are a tax on everyone who respected the calendar.
The challenge
For one month: if a meeting has no written decision in the title, decline it and ask for the decision. If you are organising, cut the invite list by a third.
I predict two things. Fewer meetings, and a strange new problem where people complain that decisions are happening without them — at which point we fix it by sending better notes, which was the answer all along.