I wouldn't zero too much beyond 50 unless you're shooting the fast sabots (1,900 fps). Slugs have too much of an arc , and you'll end up with too much difference in point of impact between the different distances.

I like to have it set up so that I'm never more than a few inches high. That way, shorter shots that can come up quickly are no-brainers. Point and shoot. When it's up close, just put the crosshairs on the top of the heart/bottom of the lungsand squeeze. If it's 2 inches high, you'restill in the center of the lungs, and you're just a bit low out at 75 yards. Never have to aim outside the fur.