Two examples of the speed of events involved in a shooting and the minute amount of reaction time that a defender has to try and counter the threat - counter the quick draw? Cover? Draw and fire back (obviously not legally available to UK civilians) ? It's hugely situational and books could be written about this subject matter /moment on the timeline alone. I present this here merely as an introduction to consider for new students before further study. The first is in a police context and the second, civilian. First example: From the YT channel "Patrick": "In this video, the reality of reaction time and the OODA loop in police shootings is demonstrated.. As well as showing the speed at which a threat can get off a shot while you are trying to decide whether they are armed. Many people doubt the logic behind Police training. Sadly, many have attended police funerals of those officers who were killed by suspects bringing a firearm out of a vehicle." Video: