When drilling on “Head Shots” in relation to STOPPING a Bad Guy IMMEDIATELY, it is VERY Important to understand BRAIN ANATOMY.
Here are two articles on the subject I highly recommend you re-read:
An important concept is to stop, look, listen, smell, and plan (SLLSP). When moving across long distances, the environment can cause you fatigue, taking away your stealthies. Conduct an SLLSP. Stop all movement. Look around the area. Listen to your surroundings. Smell the environment. Plan your route. The focus of SLLSP is to keep you in tune with your surroundings and to get your bearings while moving with camouflage. You must be slow and deliberate.