Can/should you re-use engine components?

Since I got married (1977), several of my DD family-car 318s have received well-used 340 timing chains and gears. One was so stretched I advanced it one tooth on the sprocket to get it run right. I got a whole box of those from all the 340s I ever took apart.
Most nylon-toothed 318 timing sets I have seen were already sloppy early in life. I'll guess that 80,000 was already pushing the failure date. Every 318 car I ever inspected, needed a new set.
Lemmee rephrase that; I never saw a 318 car that didn't need a new set. I mean there mightabin one in 1968, but a 3 or at most 4-year old 318 car, needed a chain; thank you Mopar for one of the earliest examples of planned obsolescence, and a steady supply of make-work for me.
But, you know; back then Mopars had a 5/50 warranty. I think likely, most 318 chains made it thru, but it wouldda been darn close.
As much as I love my Mopars, and Ma, this snafu, IMO, is utterly unforgivable; they knew better.

But-um as to the guts of the engine; Yeah you can reuse just about all the non-wearing parts.