https://blog.aopa.org/aopa/2014/02/11/roots-of-rcm/

Excellent article on how planes are _actually_ maintained.

tl;dr: the stuff you thought you knew about lifetime limits and preventative maintenance is probably wrong. Most parts don't actually wear out, and replacement parts aren't better. So planes are generally run until failure, and that's actually better in most circumstances than trying to do preventative maintenance.