[kk2002s]

So in general I have never been a replace working parts as maintenance
BUT
That was before I bought a Porsche.
While I have replaced only a couple parts that failed (Expansion tank, Climate control display, evap canister, purge valves) the rest , WP, Thermo, Motor mount, AOS, Oil cooler 'O' rings I have done because it made sense.
The org. Motor mount was bad so that was a good replace
The org. AOS was fine but 16 years old. I had bought a new as a spare and carried with me on long road trips so after a year or so I just put it in.
The org WP, Thermo, 'O' rings - I wanted to do a coolant Flush and replace so it made sense to do those components. The org. WP was in good shape

I feel with these cars and certain parts that waiting until they fail usually means a tow job, not a limp it home to fix.