My last two large orders (both this month) were a murphy bed from Costco and a mattress from Sam's. The bed was 400 pounds, was on sale for $500+ off, came in four boxes and required extensive assembly. Some of the reviews said it was a multi-day effort for two people. I had my Milwaukee power tools to help me (multitool to cut the baseboard, ratchet and drill for assembly), so my wife and I did it in about 4 1/2 hours, including the baseboard cut/removal. If I had to use manual open open end and allen wrenches, and a screwdriver it would've taken much longer. The mattress was a hybrid in a box to go on the bed, queen on sale for about $400. Both free shipping. Those are things I don't mind ordering. It's not like I'm going to walk the aisle and pick one out.
Groceries, though, I just can't get past that. We went to Publix this week, just to get things we thought might be on sale, look at the meats and such. Pork chops (BOGO), chicken, cabbage, corn, salsa, guac, some canned goods, etc. - all on sale - plus a 12-pack of beer because I hate to pay their six-pack prices. Almost everything we bought was on sale. The total was $99 and change (including tax), and the "savings" total was $49. Remove the beer ($19 and not on sale) and pure groceries were $80, less tax say about $74 with $49 in savings. We were there 20 minutes, it was part of a bank trip, another appointment and then grabbing groceries. Effortless, informed, comfortable with the quality, pleased with the service. Saw folks we knew, plus we catch up with the help, so there was a social piece. All that being said, paying full price for things at Publix without leaning on their sale items is like carrying a balance on your credit card.
Walmart isn't as fun to go to, but I try to make that trip when I've already crossed the interstate to work out, eat at Buffalo Wild Wings or make a Home Depot pilgrimage. Dog food and treats, some dry goods (Quaker rolled oats are Quaker rolled oats), oil filters, etc. Functional purchases of fungible goods at the lowest price.