For hunting use, you can pretty much take any approach that results in a hit on an animal, and you are good to go, but for target work, where every effort is made for consistency, I think it better to use a good fitting FL die every time. Cases do not get tight at the same number of firings, and if you are shooting a group in competition, and one round has an easy bolt close, and another harder, they will not group as well as if they were all hard or all easy. The bad rap that FL sizing every time gets is because of ill fitting dies. If they barely move the brass, reducing diameters a thousandth here and there, and shoulder bump is closely measured and monitored, there is no problem FL sizing every time, and this will result in the desired uniformity in bolt close effort. Unfortunately many shooters have never worked with a die that fit one of their rifle's chambers, so to them, this may seem like an unlikely assertion, but it is true.