But for some, rooting for bargains taps into ingrained opportunism. For being clever enough to pair a coupon with an item that’s already on sale. For holding off on buying a tempting pint of ripe blueberries at one store before getting it for half the price at the next. There is a devilish sense of satisfaction at having gamed the system enough to get an extra six-pack of Gillette razor blades to store in the bathroom cupboard.

The word “ritual” is thrown around colloquially today, but sometimes it still carries the weight of religious ceremony. For supermarket supershoppers, as we might call them, these stores themselves, with their floor-to-ceiling shelves and flickering freezers brimming with food that’s available fo...