Ok, I'm no good with links but I checked for your closest USPS sorting facility - and it's in Nashua! I think that means it's a high volume facility.
I also did a little reading and asked some questions of local USPS employees. When something is out for delivery and isn't delivered, in Pittsburgh, instead of going to my nearby office to wait for me (1mile from me)
it goes immediately to a bigger sorting facility (about 5 miles from me).
Then it's scanned again (could take a number of days after going through the facility doors)
then it's placed in my zip-code-whatever (bin?)
then put on a truck, driven to my po storefront
and scanned again.
if I wanted to pick it up from 5mi away it would take just as long because of the required procedure to halt it there and notify me, via the little post-it note on the front door. etc...
There are holiday volumes to factor in, number of employees doing the scanning and etc, weather, illness, has your facility cut back on hours for employees lately (around here, some facilities work around the clock, some don't).
So, don't give up yet!
And, if you type in "what is the nearest USPS sorting facility to Nashua, NH" and follow links around to The Black Hole of Richmond, CA, you'll find some interesting stories about the USPS sorting facility there, and container shipping to Hawaii, Guam, etc..
I wish I'd known this stuff before I offered to send a Big Scary Guy to help sort the packages in NYC...
Not really -
Anyway, I also can understand why an employee might not want to go into such a detailed explanation over the phone, too. They should try to explain for PR reasons, but I can see why they don't.