two day.
I just ordered a product for someone. Because the company gives priority to production on products that are shipped at a faster rate, I paid extra for the product to be shipped Two-Day Air. This means the product left Los Angeles on a plane, arrived in Memphis, and then left Memphis on another plane to arrive back in Los Angeles, where it was made, to get on a truck, to be delivered in two days. Guaranteed.
I could have ordered standard delivery and the product would have never left L.A. - or been placed on a plane - and may have arrived in a day, or two, or three, or four?
I don't know what this says about me, our culture, or our systems but it definitely says something.
We'll go a long way for certainty.