Bill Willits’ does a great job explaining the North Point model of Community Groups in his book “Creating Community.” One of the hardest things to implement in the model is multiplication- making groups split up after an agreed upon period of time (in the range of 12-24 months) and form 2 or 3 new groups.
In short, the reason for multiplication is that we have a closed group system. If you have an open group system (meaning people can be added at any time), multiplication is not necessary. People come and go all the time, and the group stays fresh. We have chosen to prioritize intimacy in our groups, so we close them. Multiplication is our answer to closed groups becoming stagnant and inner focussed. The best quote from Bill’s book on this is,
“Every group eventually comes to an end. Our perspective is that a group can plan to end and have something to show for it, or they can let their group die a long, slow death.”