Get up in a tree and the same height that you will hunt, and have your buddy move a 3D deer target all around, while you guess the yardages and shoot. Have him move it all over. Practicing in a similar environment to what your hunting is a great idea. I do this every year about 10-15 times before the opener. To me at 20ft high and 20yds or less shooting distance, there doesnt seem to be any difference. (just my OPINION)