I don't think there is a rule of thumb...Just know your limits, me personally, I don't use plates. I am a firm believer in aiming at smaller targets such bright neon stickers the size of a dime to a quarter...Personally, I can shoot really good groups at 60yds but I will never take a shot at a deer that far, I have taken a couple hogs in the 50 to 60 yd range and the furthest I have taken a deer was like 40yds, and that was pushing it for ME....You just have to figure out what your limits are and what you are confindent that you can make that shot everytime without wounding an animal, and again every shot in the woods will be different....Good luck to you!!!