It's good to keep in mind that the "overkill" approach doesn't work so well on airplanes. When you oversize one part, you are in effect making all the other parts weaker, since the total weight and hence all the loads increase.

For example, if you double all the material gauges on an airplane, the weight and the loads would also roughly double, and the strength margin would not change very much. So the real path to the strongest possible airplane is structural balance -- making everything just strong enough or stiff enough for the job, and no more. Overkill on selected parts will never get you there. In practice, structural balance is compromised for a number of reasons:

* Time and cost
* Limited gauge availability
* Manuacturing constraints
* Varying consequence of failure among parts