It could be that the convenience comes when you need scale: When I was single the idea of a gallon tub of mayonnaise was purposterous, but with a family with three children, the single tub from Costco keeps us from having to replenish multiple small jars and worrying about coupons and timing sales.
I have three children too, I kind of like timing sales. It also makes me think creatively about meals: "Oh, London broil cuts are on sale, maybe I'll make beef stew" etc. I also hate having to make multiple grocery store stops. Totally comes down to preference though, I freely admit.
