"Necessity is the mother of taking chances."
Occasionally I encounter a motorist on the highway who is driving very slowly, some 20 miles per hour slower than the flow of traffic. This driver undoubtedly believes himself to be driving in a reasonable manner, equating his slow speed with safety. Unfortunately, he fails to recognize the greater risk of a much faster car plowing into him from behind. His slow speed has made his car into a barrier rather than part of the traffic flow, and yet he cruises on, oblivious to the squealing tires and honking horns directly behind him.
Is this really a safe practice? Not on the highways in Silicon Valley.