This guy has it correct, I believe. Load development / sighting is an exercise to be able to predict, with high confidence, where the next round will land - that one shot you will take hunting. Using only one or two shots as "data" is very low degree of confidence (statistically speaking).
Once you have "statistically" high confidence, then sight in for "real". Read cool story on Internet - might even be true - writer claimed to be a US Marine shooter coached by Hathcock. Meet at range with clean rifle. Coach set up a target at to-be-determined-by-shooter range. Shooter got one shot (with cold, clean barrel) and had to tell Coach where he had hit before looking (call the shot). That was it for the day. Apparently, in their business, only cared about that one clean, cold barrel shot. Was what rifle was sighted for, eventually, if shooter could hold and release and call his shot. But need really high statistical confidence in the predictability of rifle and load to do that.