The typical modern American supermarket stocks 48,000 items, each battling for precious shelf space. How do they get there? Why are they arranged the way they are? Did you know that some stores use heat maps to track which aisles you walk down — and which ones you don't? Or that they put the milk at the end of the aisle so you're forced to pass a hundred other items on your way to get it? It's all done to gain an edge in a cutthroat business built on razor-thin margins. CNBC’s Tyler Mathisen goes behind the scenes for a...