There are guys who post on TFL that are or have been among the best shots in the world.
I represent the average guy who shoots deer, not a national level competitor.
How I sight in a rifle:
1) I take huge care that the Weaver or Picatinny mount in the front is parallel and co planar with the mount in the rear so there will be no ring lapping. A one piece scope base takes care of this without glass bedding and fixturing the bases.
2) I bore sight the rifle.
3) With the reticle adjusted the center of the scope tube, the rifle should appear to be bore sighted. If not, start over.
4) I make a chart from Quicktarget for my bullet, velocity and distance from bore center to barrel center.
5) The chart will show something like the point of impact should be 1" high at 100 yards for a 200 yard zero.
6) I go to the local 100 yard range and shoot at an 8.5"x11" target stapled at 50 yards. If it hits 4 inches to the left and 2 inches low, I then adjust up one moa and 2 moa to the right.
7) I fire another round at 50 yards. If it is close to the bullseye, I switch to shooting at 100 yards.
8) I shoot some groups at 100 yards. The big game rifles should get 1.5" groups, the varmint rifles should average 0.75" or give up on the rifle, ammo, shooter, scope, or wind situation.
9) I go to the hunting area before hunting season. I do some scouting and some target practice. I setup targets at 100, 200, 300, 400, and 500 yards. I shoot prone with a bipod like I would hunting. I use the holes in the targets to tell me how to correct my chart from step #4 above, and I rate myself for max range to shoot at game. Some years I am only good to 300 yards in wind and 400 yards in no wind. Some years with some rifles, I can keep the bullets inside a 12" kill zone centered on the bullseye out to 500 yards. I come back to my targets day after day to make sure I can put the first bullet inside the kill zone. All that getting in and out of the vehicle [you don't think I WALK 500 yards, do you?] is good practice for using the range finder and loading the gun and getting on the ground. That way when I see a deer, it is just one more target to plug.