I think you're looking at #3 the wrong way - it's not a bijection, it's meant to be surjective. Every person is meant to be responsible for one thing, but many

I think you're looking at #3 the wrong way - it's not a bijection, it's meant to be surjective. Every person is meant to be responsible for one thing, but many people may be responsible for the same thing. The aim of that is to reduce the task switching overhead from people frequently changing foci, and allow them to focus all their resources on improving one core competency.