This seems pretty reasonable to me. Maybe some of the details are wrong, I don't know. But my big question from this article is... why isn't this a well known

This seems pretty reasonable to me. Maybe some of the details are wrong, I don't know. But my big question from this article is... why isn't this a well known aspect of project planning, scheduling, and software engineering? It's not even specific to software really - I mean it's possible that software tasks have higher variance than others but I'd be surprised if task variance is irrelevant for scheduling non-software projects. Is it really the case that no one has applied mathematical modelling to the problem of project planning, scheduling and estimation before? Do the ideas in this blog post represent the core of a new avenue of research? Seems unlikely. So how come this, or something like it, wasn't taught as a basic and critical part of project planning, in the same class that taught me the term "Gantt chart"?