One had the intent to teach, and a group of people had the intent to learn.
Medicine refiners were geneticists who were originally part of the elites among interstellar humans. Their intelligence was more developed than their peers, and the majority of them had highly retentive memories and a deep grasp of profound knowledge with regards to genetic knowledge and mythological theory.
These people whom Feng Lin retained were all those who were obedient to him.
And with him personally imparting the medicinal refinement technique for the crimson refinement gunpowder, they all learned very quickly.
Feng Lin just had to demonstrate once, and they would immediately be able to learn 70% to 80% of it. They only needed to pay more attention to the minor details and practice more to achieve perfection.
If they practiced for three days, it meant three days of failure.
Even now, there wasn't any successful concoction that had left the refinement chamber.