I have to lean with Stubble on this one (like normal). Sure, you can shoot 1-2 shots to get on target near the bullseye and be pretty close, probably even close enough to get a deer or elk at 100 yards. What this fails to capitalize on however is the chance you get at the 200-300 yard animal. As with most things it all depends on your needs and situation. Like he mentioned, you're already lucky if the rifle/load is capable of 1.5" groups at 100 yards. Most are not capable of that accuracy. Then you factor in other influences such as Buck Fever, wind, angle, and poor marksmanship and your need to be very accurate starts to factor in. Plus as a rule of thumb, a 2" rifle is usually a 4" rifle at 200 yards and 6" at 300, and that's with a perfect rest (read:benchrest or machine rest). In the field you seldom get as good a rest as you'll have at the range. Since the kill area of a deer is around 6-8" a 2" rifle can barely consistantly place shots inside the kill zone at 300 yards. Add in other factors and you're lucky to have an effective killing package out to 200 yards.

For me, I shoot a lot. I'd rather put 100 rounds through my rifle every year so I know EXACTLY where that bullet will land at all ranges out to 300+ yards. I've shot 3 different elk at over 300 yards, 2 right through the heart. Where I hunt I could shoot further but I don't like shooting much past 300 as there are too many factors you can't control and wounding an animal and losing it is something I never want to do so I really have good reason to need to shoot that far. Not everyone needs that level of accuracy since the majority of shots are 100 yards or less but everyone still needs a fair level of precision no matter what the distance.

The more you shoot, the more you'll know, and knowledge is power. In my opinion every hunter owes it to the game to make the most ethical shot you can, and that means bullet placement as precisely as possible for the quickest, most humane kill. Just because you can hit an animal and eventually kill it doesn't mean that's ok.

But back on topic, I find I like to use the max magnification when sighting in. That way you can get an idea of how well you shoot as you'll see every heartbeat, and feel every wiggle when those crosshairs jump. Gives you an idea of how hard it is to be precise. I'm not a benchrest shooter, just a hunter, but considering all the BR groups use really high magnification scopes for competition I think that says something about best accuracy.