I use one, I don't range a deer when it's coming in.....I simply range all the trees in my shooting lane. Since I don't take any shots over 30yds and my Stryker strykezone 380 shots so fast and flat.....I use the same crosshairs for 20-30yds which makes things simple.....so if I had "judged" a shot at 25.....and it was actually 32....it wouldn't make a difference.