FIve years ago, coming off the town doubling in size in 5 years, the USPS here was reliable. You could practically set your watch by them. If you mailed it, it would get where it was sent in a timely fashion.
There were 'in town' and 'out of town' boses in the P.O. accessible 24/7 for outgoing mail. 'In town' mail went across town in a couple of days, max.
No more.
I have had payments cross trails, with the prior month's payment coming in after the next month's payment (thankfully with a long associated vendor, or it could have been a real mess). The first payment was over six weeks in transit.
I have had items not get delivered in a timely fashion (like the above, but items coming to me, also).
A letter mailed to a recipient across the street from the mailbox travels a minimum of 500 miles before it gets to the recipient (to Bismarck and the sorting center and back), and the 'plan' is to move the Bismarck sorting center to Fargo, which would add another 400 miles to that trip. A piece of mail would travel 900 miles to cross the street.
Small wonder my distant vendors are paid over the phone, and payments for the local ones are dropped off in person or put in drop boxes after hours.