Sorry,I didn't explain the reason why they do this. They do it to try to find a excuse to add stops to the route. This is why they try to pick a day when the weather is almost perfect,and the mail load is light. If they can intimidate the carrier into running and rushing on this one day,they hold him to this time when the mail is heavy and it's 102 degrees outside. The supervisors are always desperate to eliminate having to authorize any overtime hours because they get paid cash bonuses for coming in under budget. If they can add 100 stops to each route while still paying for he same man hours of labor,they are heroes. I can GUARANTEE you that route has changed in the last 50 years,and I can guarantee you it will change again.
Well, I actually did understand the intent - increased production. But, there's a limit to how fast and far one can walk, particularly when the bags of junk mail aren't getting any lighter. I fully understand now what you're talking about. Under perfect conditions, people can perform perfectly, but under adverse conditions, it isn't going to happen.
I used to be a meter reader for the power company up in Cleveland. We had some similar efforts to increase our meters-per-hour rate. Though we didn't have to carry the bag, we did see some increases in the length of our routes at times. But, for the most part, once a route was established, it tended to remain the same.
I was a young man back then and had no problem walking at full pace for 5 hours straight. I don't think I could keep that pace and time now. The body just would not hold up. Does the USPS account for the carrier's age when they consider the size of these routes? I didn't think so.