Following the trolley rather than cleaning the room
A delivery trolley leaves a trail. Grit from the footpath drops at the threshold, water and fine soil transfer to hard floor for several metres, and whatever remains works into carpet at the point where the route turns. By the time the trolley reaches the store, most of what it carried has already been deposited somewhere else in the building. Cleaning the store thoroughly while ignoring that trail addresses the last few metres of a much longer problem.
Walking the route at the walkthrough is what makes this visible. The surfaces change, the responsibility sometimes changes with them, and the appropriate method changes as well. Writing the route as a sequence of named surfaces, each with a frequency, produces a scope that matches the way soil actually arrives rather than the way the building is drawn. It also reveals where a route doubles back on itself, which is common in buildings that have been extended.
