I've heard many hunters say they will stop hunting the day hunting loses it's excitement. A hunter shooting his fiftieth deer may not get the shakes like he did when he shot the first one, but spotting the deer, getting ready for the shot, taking into account the awareness of the deer and all the circumstances that might affect the shot still produce adrenaline.
The experienced hunter can control the adrenaline better than the novice hunter can, so the evidence of that shot of juice might look different, but the juice is there nonetheless.
Killing a game animal should never become routine, so if it does become routine, that's when the hunter might want to think about giving it up. This week's column rambles a bit, but it includes some of my thoughts on that topic. Check it out: "Killing Never Becomes Routine."