They are storing a great deal more inventory, at least 10 to 15 percent more

That may sound like a lot, but is it really? Grocery stores churn through inventory fast. Some high-end items might sit on the shelf for weeks, but on average stores have a 3-day supply on hand. Given years of just-in-time shipping that’s strongly discouraged warehouse construction, can 10 or 15 percent expansion be significant?