Stock here is deceptive. A small fraction of the lines generates most of the takings while thousands of slow items quietly hold the working capital, and only sales data by line makes that visible.
Trade accounts are lending. Limits, statements and a routine for chasing turn a friendly arrangement into a business one, and shops without that discover the problem when a builder stops trading.
Hire stock leaves the premises. What is out, with whom, when it is due and in what condition it came back is a second inventory that behaves nothing like the shelves.
Reordering eats the mornings. Minimum levels set per line, with a supplier order generated automatically, replaces the walk round the aisles with a clipboard that most shops still do at eight in the morning.