Not yet. I would if I had a severe crash or a major mechanical issue. I hope to never quit due to fatigue.

About 20 years ago, I crashed early in a 75 mi ride. The road was wet. Railroad tracks intersected at an angle. Runners were taking up too much of the lane to croiss the tracks perpendicular; so, my bike slid on the wet rails. I had significant road rash, but I finished the ride.