Exactly. Old parts of the system will be working if you leave them undisturbed. Mechanics have very good intuitions of this sort of thing. I read about before

Exactly. Old parts of the system will be working if you leave them undisturbed. Mechanics have very good intuitions of this sort of thing. I read about before there's proper engineering / physics theory about this too, it's like a car as a machine is a linear/smooth physics system with multiple weaknesses. Overtime longtime period of running many places might weaken but it still evolves into a slightly different smooth system, until you introduce a replacement which cause a mis-match of impedance or something like that.