For motorists, over-engineering is how the engines worth buying are those which are expected to last 10 years even though they are only warranted for five years

For motorists, over-engineering is how the engines worth buying are those which are expected to last 10 years even though they are only warranted for five years. It's the way many bridges having a posted weight limit of 10tons can handle a 12ton truck without incident. If you go to all the trouble of actually engineering something to begin with, might as well include some effort into making it stand the test of time while performing beyond expectations. One of the most fundamental features of true engineering is a "margin of safety". Traditionally this is what increases the chances of your product having that most useful feature; "worth buying".