An update from me as well: though I did get a notification from Quartermaster as well, I did finally get FedEx Delivery manager set up, and I seem to get those notifications before I get the other ones. Additionally, it's pretty convenient to babysit it from the FedEx app. Getting FedEx Delivery Manager set up was a little annoying because it involved waiting for a snail mail confirmation code, but now that I got it put in, it's working nicely. I have gotten a couple notifications of delays, presumably from the winter storm going through the North ATM. I was originally baffled by that, but FedEx's logistics is a nationwide thing, so stuff slowing down in one region of the U.S. invariably throws a wrench in other parts.
Someone else here mentioned having issues with FedEx/FedEx SmartPost, which kind of bums me out because I used to work for SmartPost, so I have a soft spot for them. For those who don't know, FedEx SmartPost is a service FedEx offers for vendors to be a sort of go-between for them and the Postal Service. The vendor (Quartermaster in this case) sends a trailer full of their stuff over to a FedEx hub. It gets unloaded and sorted into trucks with other stuff that is headed in the same general direction as it. Once it gets to the closest hub, it's palletized for a local courier to pick up and deliver to your local Post Office. It is then delivered to your mailbox/door by USPS. You'll notice that SmartPost boxes have some FedEx labelling on them, but they also have a USPS barcode and tracking number. One place where packages can get hung up in this process (beyond weather of course) is waiting for a FedEx trailer to fill up so it gets sent out. I believe they do their best to ensure that all trailers are getting filled at about the same rate so none of them are sitting forever, but some are inherently busier than others. None of them took longer than 24 hours to fill up and go out that I can recall.
While I believe SmartPost is technically within the 5-7 business day range like USPS, my hub always strove to provide more Ground-like service (2-4 days). Not sure how their service is these days. I do know SmartPost never really had a "customer-facing" support, so it's hard for a customer to actually talk to anyone at a SmartPost hub and ask them, "Hey did my package go through there?" They'd always be like, "I dunno. And I also don't know where it is. And I know for sure no one from here is going to be the one delivering it to your house. Your postal worker is."