Smyrna's own housing sits in a band built between 1951 and 2004, with a median year of 1978, and that same mid-century-to-'70s core runs through the named areas we get called into most. The nearer towns - Mableton, Fair Oaks, Paces - went up fast in that same 1960s-70s wave, which means a lot of single-car and two-car garages still carry the hardware the original builder put in: lightweight steel panels, extension springs bolted to the side rail, no safety cable running through the coil.
Towns a bit farther - Powder Springs at ten miles, Hiram at fourteen - stretch the range toward the later end of that 1951-2004 span, so the mix leans newer: insulated doors, torsion springs, openers with photo-eye sensors that actually still work. By the time you get to Peachtree Corners or Union City, eighteen and nineteen miles out, you're looking at the full spread the median masks - some blocks from the '60s standing next to blocks from the 2000s.
None of this changes what a spring or a cable costs to fix. It changes what we load on the truck before we leave Smyrna. A call from an older block usually means bringing a standard-size torsion spring and a new idler bearing; a call from a newer one is more likely an opener board or a sensor-alignment fix.