Our local PO is so short staffed (USPS-provided issue) that instead of an envelope being carried by hand (from the "Local Mail Only" drop box where I deposit it on Friday) - 12' along the wall to the recipient's mailbox on the same Friday - it is all dumped in a cart with mail that is going to the rest of the USA and to lands afar, driven 180miles to an automated sorting station then hopefully my letter comes back the 180mi to my local PO where it is sorted, and placed in the recipient's mailbox days later.