The main complication in Flatwoods isn't the door itself - it's what's behind it. On a house from 1973, the header framing and the track anchoring were built to what was standard then, which is lighter than what a lot of new insulated doors want. We see this most often on single-car openings that were never widened: the door goes in fine, but the opener bracket needs extra blocking to hold securely.
The other recurring issue is weatherstripping and seal performance given the cold climate here. A door that seals fine in a mild fall install can show gaps once the temperature swings hard, especially on an opening that's slightly out of square from decades of settling. We check for square before we set the door, not after, because catching it early is a lot cheaper than a callback.
We don't try to fix a fundamentally undersized or rotted opening with trim and caulk. If the framing needs real work, we say so and price it separately, rather than let a door go in against a header that won't hold it.