Yep, that's why things are derated and safety margin is added on top of that, and everything is checked 3-5 times before it hits the manufacturing floor, where it is further checked by the assemblers for manufacturability, and then further qualification tests are performed. And when you finally get something into the field, guess what? Any problems encountered during use are tracked, mitigated to the greatest extent feasible, and the data is fed back into future designs.

(I work for an engineering firm)