In the boost phase of a newly launched idea, it's actually a really good idea to train teachers. That gives you exponential growth.

Most memes that grow exponentially do not manage to stay sane. What's best for the exponential growth of a meme (as though it were a bacterium with no identity other than itself) may not be best for the culturation of a cause. Exponential growth is good, I agree, but the fastest possible exponential growth... seems more doubtful.

Exponential growth around friends giving friends copies of a fixed book, seems safer and shallower; the book won't change as it's passed around. The building-up of rationality dojos is a longer, slower endeavor which should be more carefully gotten right.

Plus you can look for students who've already done something interesting with their lives and train them to be the teachers.