Standing in front of the fridge takes longer than you think. Are there eggs? How much milk is left? Is the miso in the front or the back? Open, search with your eyes, close the door. And later at the store checkout, when you suddenly wonder if you forgot something, you're usually following the thread of that moment of uncertainty back home.
After assigning each item a fixed spot inside the fridge, shopping lists became faster to write, the store felt easier to navigate, and collectively those small efficiencies saved about 30 seconds each time.