There is always a goal for gathering. Inviting friends over for dinner can serve to build and continue relationships and ongoing dialogues. Attending a professional conference can serve to grow a knowledge base or collaborate/communicate with colleagues. These goals can be formal or informal, specific or general, short-term or long-term- the list goes on and on.
The most effective gatherings, the ones that people remember, have a clear and specific goal. The most effective gatherings make decisions based on the goal. The most effective gatherings stay true to the goal.
A meeting is just one type of gathering. It shouldn’t play by different rules.
If the goal is of a meeting is to brainstorm solutions to a recent software implementation failure, the meeting ends when the brainstorming is complete. If the goal of a meeting is to make a decision on the color palette for a logo, the meeting ends when the palette is chosen. Don’t hold your colleagues hostage as you try to fit multiple (newly identified) purposes into that time.
“I really wish we used the full four hours for that even though we got what we needed in the first ten minutes.” – No one ever
Goal met? End it.