Heat is the thing that shortens a torsion spring's life out here, and it does it through cycling, not through one bad day. A spring loses a little temper every time it heats and cools under load, and in a climate with a long severe-heat season, that happens more times per year than it would somewhere milder. On a door built around 2007, that's roughly a couple decades of hot-cold cycling on hardware that was never top-of-the-line to begin with.
With only a few hundred households in this immediate area, we're not out here every week the way we are in the bigger parts of the service area - but the door type and the failure pattern are consistent enough that when a St. Johns call comes in, we generally know what we're going to find before the truck leaves Goodyear.