I have seen occasional delays, and when you look at the tracking info, it seems like the package bounces around from location to location. Example I had was I mailed a package from my post office (northern Illinois) to Massachusetts - it took a week to make it through several Chicago USPS hubs, then went to North Carolina, then back to Chicago, then to several hubs on the east coast before finally making it to Massachusetts. So that was kind of frustrating.
I have another very recent experience I was wondering if anyone has had. I received a note this week from Etsy stating that USPS needed to make an adjustment to my shipping label cost - they claimed the package I said weighed 6oz actually weighed 4lb,13oz. This is ridiculous. I was shipping a nice coffee scoop with a Thuya Burl handle - the package weighed 6 ounces. There is no way it was even close to the weight claimed by the USPS. I even confirmed with my customer that my package arrived as expected and was only the coffee scoop (I was wondering if, somehow, USPS misidentified my package.) Anyway, USPS more than doubled my postage fee (from $4.43 to $10.17). I have contested it. I looked online, and apparently this is not a rare occurrence. There are a lot of angry postal customers getting arbitrary upcharges.