After 3 days I assumed my "overnight" pack was lost, stolen, or seized. Even my friend who used to work for USPS said there was a 99% chance it was lost for good after it had been 4 days with no tracking update
But after the tracking not updating for 6 days it magically appears at my local PO and makes it to my mailbox a couple hours later
So next time you're waiting on a late pack pray to the drug mail gods and perhaps they will bless you with good fortunes
Simple explanation: The vendor didn't send it out when he claimed to have (a common occurance).