[Oh Haha]

Fred-you are correct about the driver not having an extra second. Some drivers can handle being pushed and always under the gun,others simply won't.

We implemented a program before I left that was based on the UPS routing system. It literally gives the drivers a certain amount of time to get their route done.

Our drivers had to load containers so they were "allowed" x amount of time per container, based on industry standards. We could plug in different parameters for each stop if it applied which would give the driver a bit more time for delays.
Unless they had a good reason, they couldn't vary from the routing on roads, either.

As manager, I would have to dissect their day and then ask why it took longer than what "the plan" said it should. It was not the best part of my job. Sitting down with the driver at the end of a 10,11,or 12 hour shift to point where they did wrong didn't promote a happy workplace.