My best suggestion is don't use USPS and go with something else if you have the option. USPS has had to cut back on manpower and equipment within the last few years, and are pretty much under-funded.
The option wasn't given, and if it was, I would have chosen DHL or FedEx since they've been the best I've had so far.
The seller didn't want to go through a courier, just wanted to quickly dump the parcel off at their local post office and be done with it. Originally, they weren't even shipping it outside America, because of how expensive shipping is.
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What annoys me most about USPS tracking is just how inconsistent it is. Some have the customs clearance message, others don't, some have the "onboard with driver", others don't etc etc. Very weird.
EDIT: So, the most common occurrence is that the package will be delivered 2 days after it arrives in the country, and for me that's tomorrow. There are few cases where it took 4 or so days later, but they seem to be outstanding cases.
My hope is that the contractor who delivers it is either the guy I'm used to, who always arrives at about 10AM or 11AM on the dot, or it's another guy who arrives about the same time, maybe even earlier. I got college at 1PM and it takes an hour to get there, and I'm going to be pissed if I get the loving card.