Movements are essentially all about "speed of doubling."

No matter where you are in the world, no matter who you are working among, no matter how many believers you have, it will typically not take more than 17 "doublings" of the Christian population to saturate most districts.

20 to 25 doubles would suffice for nearly any province. 32 doubles would see the entire world Christian--even if you are starting with just one person.