Oerter's feat still the more impessive

Al Oerter won the Olympic title in the discus in the 1956, 1960, 1964 and 1968 Olympics. Only four. That is a paltry sum beside Michael Phelps' total, but consider that discus throwers only have one event in which they can compete. Oh, they might try the  shot put, but that is not likely. The nature of the event is such that it pretty much stands alone. In swimming you have freestyle, butterfly, backstroke, individual medley, and who knows what all else - plus the relays. Lots of places where you can compete for medals.