The speaker argues that expertise requires learning from more than one case; most people have a sample size of about five, while someone who reaches about fifty cases is probably among the top people in the field.

“And then you will learn, and that's the only... Like, your sample size has to be more than one, and most people's sample size is, like, five. But, like, you know, if you can get it up to, like, fifty then, like, you probably are one of the top in the field anyway.”