Periodic service is actually what we called preventive maintenance (PM) in the military. Its why, for example, the 2 1/2 ton trucks the USArmy used in Desert Storm performed so well, never mind most of them were built in the USA in the early 1950's.
PM includes inspections as well as fluid and parts exchange. You may can sometimes skip some things, but how to know what and when something is weak, loose, excessively worn? PM is is, in my humble opinion, very necessary for safety, reliability, and long life(maybe yours as well as the cars).
It's the cheapest insurance you can buy for an auto.
Just an old soldier's $0.02.
'75 240D 300000 miles