Do you develop software? Software unlike any physical engineering field. The complexity of any project beyond the most trivial is beyond human ability to work with. You have to switch from analytic tools to more probabilistic tools. That where "feels", "smells", or "looks" come in. Software testing is not a solved problem, unlike bridge testing.

So many FOSS software are made and maintained by a single person. Much more are developer by a very small teams. Probabilistic aren’t needed anywhere.