This is a thing, but there are a million edge cases that you can’t rely on this for. Sometimes you underestimate the amount of material you need, sometimes you need to make sure that the sheets of drywall you’re getting aren’t damaged, sometimes you need to pick individual pieces of lumber from the pile because there is a ton of variation in the grain etc etc

If you’re doing a project you very much need to be able to run to Home Depot that same day and pick up additional bulky items.