In some cases, an incredibly aggressive supply chain and payment schedule can actually create financing for a company. Aswath Damodaran's corporate finance class mentions one of the major alkaline battery producers as an example. At any point, they only have 2 days worth of production in inventory, and they require payment within ~7 days from clients, while their own suppliers are paid after 30 days. That means at any point, they are holding about 20 days of revenue worth of cash without paying any interest.
Its not purely cashIn-cashOut, there is a time property as well, and various forms of investment can make cash_t1>cash_t0
I have read that something like 5% of Starbucks' accounting liabilities are gift cards that have not yet been redeemed. So again in a simplified financial view, that is a loan at 0% interest, and some percentage of that "loan" will never get called in.
I guarantee you they have models about what percent and at what rate over time that "loan" actually gets "called in" (redeemed for coffee and store employees' time).
I have a few supermarket chains within reasonable shopping distance. The higher end one seems to be low in stock of a few staple items.
The more mid-tier grocer has no shortages that I saw.
My guess is they warehouse things differently.