Why don’t you ask Coles Myer how they carry out stocktakes in their warehouses.

I’ll
tell you how. A day is set aside to hand count stock in the warehouse.
They have their warehouse staff count all stock by hand at ground and
head height. Above that, it’s counted by looking and attempting to
count by sight. Guessing.

Where I work (it’s a medium warehouse) they regurarly have up to a
million dollars worth of stock still in the warehouse when their
records indicate it should have been sent to the stores. It’s a bit
like the corner storekeeper taking a guess at what he or she may have
on the shelf when they want to re-order stock.