The "correct" way to shop at Costco is to wind through every aisle. They want you to discover what they have - what's new, what's gone, what's on sale, try some samples etc. There are some general anchors like the fridge, the alcohol, the produce section but it's otherwise pretty ephemeral.

It's not the kind of place where you go in with a shopping list, make point-to-point pickups and then checkout.