Due to the nature of the business there are some senior maintenance people who work nights and are expected to handle emergency equipment failures rapidly and effectively. I would imagine they stand around with their thumbs (you know where) if they do their jobs right the first time.
Then there are the air conditioning guys. USPS doesn't pay enough so they have to constantly train new AC people.
Oh, a luxury item, AC in the post office ~ sure ~ what happens is mail is paper. A modest rise in temperature brings a modest rise in humidity and the paper doesn't move correctly through the mechanized systems. Next thing you know the mail is not getting sorted, and when that happens delivery is delayed.
There are many USPS managers who'd be happy to dispense with the AC systems ~ they're costly and require maintenance. But, the public would have them flensed.
When I go to the Post Office there is one guy who services most of the people in line while the other 3 diddle around taking 1 customer to his 3 to 4. The guy is a hard worker, and he probably makes the same as the ones lazing around working in slow motion. Government needs to cut 50% of their workers, unfortunately the hard worker will be one of the ones cut because he was working too hard to spend any time kissing backside.