Why stitched master decks miss the point.
Every Monday, the asset manager opens the master deck. Numbers from 22 property reports, pasted into one slide. By Tuesday, the property-level dashboards have ticked and the master deck doesn't reconcile. By Friday, no one trusts the portfolio number.
Aggregation at the data layer fixes that. Portfolio metrics and property metrics are computed from the same data spine, so they always tie. The portfolio number is the property numbers - by construction - and the portfolio view updates within 90 seconds of any property-level change.