DJ short says he picks out of at least 50, which Ime means he picks out of 50 viable beans. So a bit more than 20 but way less than 100. Breeding is about a lot more than just "good genetics doing the work" because you can have all the most fire genetics in the world and still have not a single compatible pair. Some strains/plants just don't like each other. Bodhi is amazing at finding males that meld into his elite females. DJ short has his light schedule during flower to find phenos that most growers won't in their setups at home. Bog makes good shot as well, but again you'll see he uses the same males to cross with all of the females he works into his lines.
Good genetics only get you so far, check out all these new breeders crossing fire genetics and throwing herms left and right. You need to know how and what to cross. And then test what you THINK will cross well, because you really never know until you grow out the offspring. In my breeding projects I go through a lot more seeds than most just to find seedlings I think make the cut so I'm into the numbers game, but I'm not going to say for sure that you can't breed with 20 plants selections. Because I think that that is an incorrect statement.
And I never stated anyone is creating a strain in one generation lol. Try 5-7 min.