Here is the thing about a town where most of the housing went up in the same twenty-year window. Everything in those houses was installed at the same time, and it all reaches the end of its service life at roughly the same time too.
Kitchens and baths come first, usually for two reasons at once. The finishes are worn, and the layout belongs to a different era. A 1985 kitchen was designed as a closed room with a doorway to the dining room, and the single most requested change we handle in this town is opening that wall. That is structural work rather than cosmetic, which is why it needs a general contractor holding a Construction Supervisor License rather than a cabinet installer. Our kitchen page covers what removing a load-bearing wall actually involves.
Then the exterior, all at once. Windows, siding, roofing, and decks were installed together and tend to fail together. A pressure treated deck from the late 1980s is well past its expected life, and the ledger connection on a deck of that vintage is worth having somebody look at regardless of what you plan to do with it.
And insulation is usually the quiet opportunity. Houses built before the modern energy code have far less wall and attic insulation than current standards, and a re-side is the cheapest moment in a house's life to fix that.
The upside of all this is predictability. When we open a wall in a house from 1983, we generally find what we expected to find. That is not true in Worcester or Leominster, and it means a Southborough estimate holds better than one on a house from 1890.