^^^ What TN Lone Wolf and Timbrhuntr said. Yes, it's nice to shoot at the distances you're going to shoot animals at so you get practice at shooting longer distances. But, a lot of guys don't have access to long distance ranges and instead use some version of sighting their rifle about 2-3" high at 100 yards so they know they're covered for up to 300 yards at least. It worked well for Jack O'Connor and has worked well for thousands of other hunters as well. IMHO, it's more important to get out and practice your shooting often so you keep a perishable skill intact and know your scope is still working okay.
Some purists will disagree but there's nothing wrong with that. In a perfect world, each of us would be able to practice shooting at the exact distance we shoot at animals so we "know" we can make that shot. If you're being a true purist, however, doing so means that you shoot at each 1 yard increment up to and past any range you anticipate shooting at an animal. That's a lot of shooting (nothing wrong with that) and a lot of ammo (harder to come by these days). If you use the O'Connor method, you could shoot a box or 2 of ammo from likely field shooting positions at a 100 yards or so and get a lot of realistic field shooting practice without breaking the bank.