Stock is committed, not owned. Four hundred plates are worthless on a Saturday if three hundred are already at a wedding, so availability has to be read as a calendar rather than as a number in a warehouse.
The count at both ends is the business. What went out, what came back and what broke has to be recorded per hire, because a discrepancy noticed a week later cannot be attributed to anybody.
Washing sets the rhythm. Items returned on Sunday and needed on Tuesday have to be through the dishwasher and repacked in between, so turnaround is what really determines how many events a season holds.
Small losses become large ones. Two glasses here and a serving spoon there is invisible per event and substantial per year, and only per-hire records reveal which customers and which items account for it.