wrote

The most successful mail-order businesses ship the same day. I got an
order from McMaster-Carr within 48 hours (8:00PM Monday to Wednesday's
mail)
of placing the online order.

That would be an exception for me. McMaster delivery is next day if I have
the order in by 5. The rare exception is if the item has to ship from
another location. Our shipments come out of Chelmsford, MA.