Calculations putting the worst case into everything will often result in over-engineering, which might be acceptable in safety critical applications, but otherwise counterproductive.
Somehow, this is evolving a bit into a Pub discussion, which I like... but we should rather meet there
! won't rub your nose in British car manufacturing that used your approach vs. "German over engineering". It's history.
You take a Pint, I'll take a Mass.
Cheers.