Rather than seeing what kind of punishing temperatures one can endure to please their thermostat, other options are available that I consider more intelligent. An attic fan, thicker insulation, whole-house fan, window maintenance, sealing air gaps, etc. While there is the demographic that has an empty house while they're gone at work, most have a family, pets, etc. that should not be subject to varying extremes of temperatures. Instead of focusing on when to adjust temperature for human conditions for the sake of saving energy (and money), the house should probably be sealed better to retain the temperature with minimal machinery involvement. The Nest is a cool gadget, but very limited in actual value in its current implementation.