I haven't exceeded the fatigue life of my 88 Cannondale Crit bike. She's got way over 40000 miles on her and her aluminum fork. She does get checked 2x a year, cause she still gets ridden in crits.
It's the 01 DeRosa MerakI worry about. She has a 2 lb frame, which I worry was built to the edge of engineering. It is a Dedaccia 6061SC tubeset, which claims to be micro-shot peened (KET is what they call it) to prevent fatigue related problems. She also claims a 185 lb. rider limit. I check her for cracks too.
I think the heat treatment is what raises the cost on 6061-T6. Doing it right takes time and knowledge and equipment.
Does anyone know what alloy flexy old Vitus aluminum frames were made from ? They weren't known for breaking, even at the bonded lugs.