The 38% sample allows you to build a model of the population distribution based on which you take your decision. But this does not mean you have to do this EVE

The 38% sample allows you to build a model of the population distribution based on which you take your decision. But this does not mean you have to do this EVERY time. Say you have done a round on interviews before and you are tasked with interviewing for a new position: you might hire the first person you speak with because you know the population model, and they are high up with respect to that. In common parlance, this is called "being experienced"