@FryingMan What you say is correct but not completely. For example when visualizing you get better and better at it while doing it. Athletes rely on repair, they destroy cells or make them tired and while repairing the body makes it come back stronger than it was before, that's also a delay. I should come up with more examples to prove that LDing can have immediate improvement observation and that other things can have delays, but I tell you that all skills are basically the same at a deeper level.
About the 20 hours thing: Maybe he meant that if you spend 20 hours at doing something, you will at least know how to practice the skill. I didn't watch the video btw