That's easy to believe. My job was running Special Deliveries, and doing a collection box & substation station collector route. Some presorting etc in the "slack" times.
The highlight of my 'career' was being late for Dispatch, after my last pickup, IF I stuck to my official route. I was in a Dodge station wagon "school bus" that was borrowed for Christmas rush. It had a 440 Magnum in it, so I hopped on the freeway, at night in the rain, to shortcut back, and passed the Superintendent of the Mails while hitting 105-110.
Since the school district had loaned us several of these vehicles, they couldn't prove it was me. I made Dispatch.
He had his family with him, and gave up trying to get a number (couldn't) when he hit 75 and was being left in the dust. We all got an earful from him when he finally got to the P.O.!