In the traditional approach to engineering system design, engineers usually come up with several possible designs, each improving on the previous ones. In coming up with these designs, they try their best to make sure that their designs stay within the safety and other constraints, to avoid potential catastrophic crashes. The need for these safety constraints makes this design process reasonably slow. Software engineering at first followed the same pattern, but then realized that since in most cases, failure of a software test does not lead to a catastrophe, it is much faster to first ignore constraints and then adjust the resulting non-compliant designs so that the constrains will be satisfied. Lately, a similar "move fast and break things" approach was applied to engineering design as well, especially when designing autonomous systems whose failure-when-testing is not catastrophic. In this paper, we provide a simple mathematical model explaining, in quantitative terms, why moving fast and breaking things makes sense.