Extreme spread is a very fickle statistic--especially when applied to the relatively few shots in a typical hunter fires when working up loads. Even standard deviation doesn't mean anything when firing a 5-shot string (much less a 3-shot string). Ammunition companies generally fire dozens of rounds when testing for consistent SD.
This still doesn't mean their ammo will always be reasonably accurate in a wide variety of rifles, because the rifles themselves vary too much. But in general there's a better chance of consistent accuracy than the "pet loads" of many handloaders, many of which are based on a single 3-shot group.
