A BIM model's accuracy starts decaying the moment construction begins — and it only stays honest if someone keeps deliberately updating it.
"The BIM model" sounds like a single, permanent thing — built once during design, then simply true forever after. It isn't. A BIM model is a snapshot of what someone believed about a building at a specific moment, and that belief starts drifting away from physical reality the instant construction begins. The model only catches back up when someone puts in deliberate effort to update it — and that has to happen not once, but again and again, at every stage of the building's life. Facility teams that treat a single BIM deliverable as permanently accurate are, in a very literal sense, planning renovations and emergency response around a building that no longer exists.