Holds the cross-project capacity model, the standing priorities, the daily standup. Catches drift between what was planned and what's getting done. Three things per window — no more.
The PM discipline. Sits across every project Articulate runs — client work, own-business work, infrastructure. Holds the capacity model. Knows what's running, what's blocked, what's been quietly abandoned. The voice that asks "what gets pushed off the desk to fit this in" before anything new is committed.
If a fourth thing is "also important," it's not actually a priority — it's a wish. The discipline is that three per window forces the conversation that matters. Capacity is the most-constrained resource in the operation; the weekly model exists so nobody pretends otherwise.