Only somewhat related, but last year I learned that standard USPS tracking numbers are reused after 120 days, which can cause some really bizarre issues for package tracking apps. I reached out to the developer for the app I use, thinking it was a bug because I had received a tracking number that showed the item had been delivered to a different state about five months previously. It’s truly bizarre (source):
I find Informed Delivery useful just for overall notifications on mail I wasn’t expecting (mostly greeting cards and the like) or important paper documents so I know to look out for them. But it definitely varies on which day I actually receive the items.
It’s a bit of an older thread, but you may find this interesting/horrifying: