I don’t believe the classic team sizes of 7 (+- 2) people. I feel that those teams are too large to have meaningful conversations.
My rule of thumb for a team which I’m comfortable in is the dinner table heuristic with an ideal size of 3-4 people.
The dinner table heuristic explained
Imagine you’re having dinner. If you are 2 people you can have a close conversation and both of you part take actively without problem. A two person conversation is more intense than others since you will have eye contact all the time.
At 3 or 4 people the conversation is still easy. Since you can slip in and out of taking an active part if you wish, the conversation is less intense than with just two people. At 4, you might split up into two pairs but it isn’t necessary to in order to feel that the conversation is even. It might even feel a bit strange to not have the conversation in the full group.
Larger than one dinner table
At 5, something happens. The awkwardness at dinner of being an odd number and having to occupy a four person table plus one is echoed in the conversation (no one wants to be that odd person out sitting with an empty chair in front!).
You will either try to keep everyone in the loop or you will start to split up into subgroups with 2 and 3 people. If you split up, instead of one conversation, the dinner party has several simultaneous. If you try to stay within the same conversation, your average speaking time is 12 minutes per hour.
At 6, frustration is starting to make itself known if you want everyone to take part. Otherwise, subgroups of 4+2, 2+2+2 or 3+3 will form.
At 7, you spend less than 9 minutes per person and hour speaking in average, which 15% of the time. Because it’s harder to try to participate, some people will disappear from the conversation by staying quiet. You are possibly interrupting each other since it is harder to find an appropriate time to speak. Not only that, but booking a restaurant table for your team activity is starting to get difficult.
Beyond this, it just gets harder and harder with less and less time per person to speak.
Let’s look at the quality of the conversation.
In a setting with for example 7 participants, some people lack the energy to participate and battle for their space and we loose their insight and opinions.
Instead we get only the opinions of the outspoken and extroverts who have the energy to make room for themselves.
You can also spot some people who aren’t actively listening. They are just waiting for their turn to speak because finding that gap is crucial to be able to say your piece.
When individuals don’t have a natural space to talk to each other, risks and concerns might not be voiced. Engagement goes down as well as the feeling of having fun or being appreciated.
There is something which happens when your team reaches 5 people. It’s the first time subgroups naturally start to form because it’s easier that way. If you want your team to have have the possibility to easily have meaningful and rewarding conversations, it might be an idea to limit the size of your team.