On some of my longest run or rides, I am careful to not go past 80 or 90%. One never knows when one will require an extra gear. This reminds me that the most reserve that I have ever exercised was outside of Monterrey, NL, Mexico. I headed west just prior to the setting of the sun and on the way back I started to jog in the middle of the highway to get my butt back in the city. I turned my reflective shirt inside out, and kept looking for dogs/coyotes. When I made it to the Hotel, I left three strays at the door.
I presume you have all seen the vid of the 80 year-old ex-Indian army officer who put a beat-down on the Halloween mask-wearing thug with a gun?