Why statisticians prefer scoring good on average over exceptional only once

How scores turn out can be surprising, whether they come from sports or medicine. In sports we like the excitement: even the best-known favourites have only one opportunity to win at the Olympic Games or in a World Championship final. But what happens when a clinical study relies only on a single measurement? In such a case we should be careful with the promises of personalized medicine and precision medicine. Medical science cannot do without repetition and averages.