You're probably right that sometimes people are hiding something from you. But I think a lot of the time it's more like "I have 10 people doing a bunch of thing

You're probably right that sometimes people are hiding something from you. But I think a lot of the time it's more like "I have 10 people doing a bunch of things that vary over time and on a day to day basis, and what each of them does specifically really depends on what they are good at and what comes up. I really want those 10 people to be able to do 10% more of that confusing mix of activities than they are currently doing. So I guess I'll hire someone new." And when that new person asks what they will be doing, the answer actually is, honestly, sort of ambiguous. It's not a great sign for how organized they are, but it's still a realistic way someone could both be hiring and not know exactly what the new person's day to day will be like.