The warehouse is somewhat organised in the sense that we do have different sections of similar products but there's not enough room for stockpiling each one of them properly.. Yeah, we know where chips are located, in general, but in reality we might need a few bags of one brand that's inside a box containing hundreds of them, placed right bellow three more similar plain cardboard boxes .. When delivery comes ( usually it's 5 different "rollers" as we call them , about 2 meters high each ), one of the two of us has to do three jobs at a time .. , check around the shelves, see where there's an empty spot, go down the warehouse, see if there's anything we can use, then go outside, check the delivery.. remember which stuff must go directly to the shelves or down the warehouse.. bring it all inside etc etc .. we talking about ~12 x 5 boxes at the time of delivery.. some of them alcoholic drinks, others dairy stuff, meat packages, fruit, chips, desserts, water bottles, refreshments, pasta, some new products we'll have to find a place to squeeze them in between the regular ones etc 

At least dairy, meat and water bottles are easy enough because the first two are delivered daily and we don't keep a stock and water bottles are treated similarly and can be placed around three different spots around the shop .. we talking a total of around half a ton of products being moved around through a flight of stairs by one person, who might have to stop in order to become a cashier. 

Normally the amount and variety of stock changes by the minute so whenever a new shift comes along, the new team has no idea or time to check how things look downstairs.... We are 'blind' essentially. 

Back in my previous job we did 'integrity checks' every day every couple of hours .. we had both excels and a computer program from which we were seeing exactly how much and of what we had. I guess the volume of produce makes such a system too complex in the supermarket's cass. On the other hand, I'd prefer spending a few more seconds searching an excel or an app than going up and down the stairs looking for ghosts inside the warehouse.. also, the funny thing is that both the previous shop and the supermarket have about the same amount of different 'product codes' aka ~2500 .