Define works? Ive seen stupid and not working but convinced it's working until proven otherwise... I use to work part time restoring Fiat, Porsche, and VW rare

Define works? Ive seen stupid and not working but convinced it's working until proven otherwise... I use to work part time restoring Fiat, Porsche, and VW rares for an old head out in the mid west, lots of "stupid but works" in those old cars... Mercedes Benz once (1980s or so) employed glass containers to solve for fuel pressure problems. Insane coolant loop designs or early Fuel Injection systems that develop "Ghosts" lol...