Track 1 gets delivery on Monday, Wednesday and Friday. Track 2 gets delivery on Tuesday, Thursday and Saturday.
The worst thing that happens is that you get half your mail a day later. If you don't like that, rent a P.O. Box and pick it up yourself every day.
I have had some thoughts along those lines as well. While that would reduce fuel costs and wear and tear on vehicles, I’m not sure how many employees could be cut. And it would only work for residential routes.