The math on a spring is simple: it's rated for a number of open-close cycles, and it wears down whether the door is fifteen years old or thirty. What's different about Midlothian compared to older parts of the wider service area is the build date. The typical house here dates to around 2006, well past the 1976-2014 range and later than the 1980s-90s stock that dominates a lot of the surrounding towns. That means the springs failing now on Midlothian doors are mostly original springs on original doors reaching the end of a normal service life, not old torsion units on hardware that's been swapped once already. Heat is the other factor - this area sits in a moderate-heat climate band, and summer heat cycles the steel through expansion and contraction that adds up over years, same as it does on any door, just steadily rather than dramatically. With roughly 12,140 households in Midlothian and most of that stock built in the same twenty-year window, we're seeing a fair number of first-time spring failures on doors that have simply hit their mileage.