The rule of 3 and 10: group life still working?

Humans like routine. Group life is no different. Before you know it, things just “go like that”, “work that way”, and “have always been like this”. Of course, routines break all the time. The rule of 3 and 10 predicts that routines stop working when the number of group members changes. But even if it doesn’t, rethinking group life from time to time keeps your group healthy.

still working?

Organic growth

Every group has its own life. You have certain meetings, certain ways to communicate, and certain ways to do things.

A lot of these aspects of group life develop by themselves, driven by the people of the team. Some things, of course, you decide in the beginning, such as the kind of meetings you will have and when.

Things stop working

Sometimes, what worked really well for a while just stops working. Meetings get so boring that you can hardly keep your eyes open, and people start texting instead of listening.

Communication fails: tasks are forgotten, important messages aren’t delivered.

Information becomes hard to find: team members just don’t find the info they need, and start reinventing the wheel.

Take action before it’s needed

If you look out for it, you can catch these kinds of decline well in advance. On a regular basis, ask yourself and your team whether things are still going well:

  • Are meetings still effective and instructive? Have the regular building blocks of your meetings become boring? Have they lost their purpose?
  • Are you even having the right meetings? Are the right people attending? Can some people stop attending?
  • Are the organically grown processes still efficient and effective? Where does information get lost, and where is the way things are done complicated or annoying?

Together with your team, find better ways and improve things. It doesn’t have to take long.

I put meeting evaluations on my calendar every 3 months, and just ask at the beginning of a meeting what everyone thinks could be done differently. Nothing’s built in stone.

The rule of 3 and 10

Grown group structures become obsolete especially when the number of team members changes. Phil Libin, the founder of Evernote, reports that pretty much all processes need overhaul whenever group size triples or reaches the next order of magnitude. So, from being alone to being 3; from 3 to 10; 10 to 30; 30 to 100.

In science, most groups won’t reach 100 members. But the lab I used to work in grew from 4 to 40 within some 7 years. I didn’t know the 3/10 rule, but looking back, I can see how things broke and needed fixing.

Group growth can go much faster than you anticipate. Over the last couple of years, my core group was 5 people, but we had a flow of student assistants, BSc and MSc students. In the blink of an eye, a group meeting grew from 5 to 15. And indeed, we changed the meeting structure. New people, new needs.

Keep your eyes and ears open.

Leave a note about how you go about changing your lab’s routines in the comments below!


The rule of 3 and 10 was passed on from Hiroshi Mikitani to Phil Libin, the founder of Evernote. Read more about it here.

Photo credit: jeffeaton / Foter / CC BY-SA

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