Oil Coolers

In October, after an extensive repair/restoration of my airplane, the
oil cooler split on start-up and dumped most of the oil. Long story, but
the engine seized up 6 minutes into the flight and we did an emergency
landing in the desert. We were very fortunate to walk away with minor
injuries, but the plane was totaled.

To the airplane owners out there, how often do you flush/pressure test
or replace your oil cooler? Some say it's only done at a major overhaul,
others say it should be done at every annual, others say only if there's
a problem w/oil pressure. I had never heard of an oil cooler failing
before this, but now I've heard people say it happens on occasion.

Anyone else here have experience with this?

Shirl