Doubling groups is a worthy goal. Here is why.

There is another reason why this is a worthy goal. There is no disciple-making without small groups. God’s plan for forming spiritually mature disciples involves getting them in groups. People do not climb Mt. Everest alone. But every year, little groups, little platoons, little bands of friends, scale its lofty heights.

People do not reach spiritual maturity alone. But in groups, with friends, in little platoons they can reach maturity and have fun while they do it. It will not be easy, but it can be fun.
Josh Hunt. You Can Double Your Class in Two Years or Less.