We are all still learning. Each new rifle or barrel is a new learning experience. Once everything is "down pat" for a given rifle, trying other combinations, say of target size, loads (patches or size of ball) conditions, as in comparisons of different weather on the load's accuracy and point of impact, all from the bench to eliminate poor holding, can also be a good teaching tool.
The smaller the bore, the more 'testing' must be done. The larger the bore, the more forgiving the rifle becomes.
For example, my 14 bore rifle's sights have not been moved since she was sighted in back in 1986. The loads have changed slightly, with 3 drams of 2f GOEX being my go-to load now for close range trail walks, instead of 82gr. 3F. Today, the 2F gives same the same velocity and POI as 3F gave years ago, 1,225fps. My hunting load of 165gr. 2f GOEX has been reduced to 140gr. 2F GOEX- my 200yard sight is still zero'd at 200yards. With 165gr. fo today's 2F, that sight is zeroed at 200 meters (220yards).
Thus, experimentation of one sort or another is never really done - it just gets easier or is more quickly accomplished.