The trouble starts when someone brings a standard-size torsion spring to a non-standard door. A 1992-era estate door in Fairbanks Ranch often isn't a stock 8-by-7 or 16-by-7 - it can be a custom width to match the house, which means the spring wind and wire gauge have to be calculated for that specific door's weight, not pulled off a shelf sized for a typical tract home. Get that wrong and the door either won't hold position or slams the last foot of travel. The other place this goes sideways is the opener. A door heavy enough to need dual springs is often too heavy for a builder-grade chain-drive opener from the same era, and that opener straining against the load is usually what fails next, not the door itself. We measure the actual door - width, height, panel material, and existing spring wind - before ordering anything, rather than guessing off the house's age alone.