Reaction times vary between individuals and even between an individual depending on context. Being hungover, tired, on the phone, lost in thought, reading a bi

Reaction times vary between individuals and even between an individual depending on context. Being hungover, tired, on the phone, lost in thought, reading a billboard, or fiddling with a stereo can significantly impact reaction time. Additionally the stopping distance varies between vehicles and even base on external factors like road conditions, weather or ol'Musky pushing a firmware update. Following too closely is vague and only enforced after an accident because of these variances. I was once told by a driving instructor that the safe following distance behind a car is always 3 seconds regardless of speed. At 3 seconds distance there are no evasive stopping actions and your underwear remains unsoiled.