The on-call rota is the org chart
The names that get called at 02:14 are not the names in the org chart. The rota is the truer view of the company. The org chart is fiction.
In every retail ops setup we have looked at, the people named on the rota are not the people in the org chart. The rota has names, phone numbers, escalation order. The org chart has job titles. The rota is the work. The org chart is fiction.
Org charts are designed for HR, payroll, and the meetings that produce no work. Rotas are designed for the alarm at 03:00. The one that matters is the one that gets answered. When the chiller fails at 02:14, the rota has a name, a number, and a pickup-time guarantee. The org chart has a Director of Operations and an out-of-office reply.
The on-call rotation on the anonymised retail chain (the same 84-site engagement as mission-control) is five regional managers plus one duty officer plus a director for escalation. Seven names on the rota. Forty-three on the org chart.
The lesson does not generalise. It generalises to operations. In product, marketing, design, the org chart is closer to the truth. In operations, the rota is closer. The instrument is the role.
The signal is in the names, not the titles.