Plus you could write on the card file where they worked or where their second cousin lived if you happened to be out that way
I covered a route that the driver had five drawers of cards welded together. He had the directions down to the tenth of a mile. His directions were actually too hard to follow because of the detail.
I bid on a route with a kind of sketchy file, because the driver lived in the area, so the detail wasn't there.
We had just gotten our first computer around then, and I set up a database file in Appleworks instead of a card file. I put a lot of time in at first (mostly because I wanted to learn how to do stuff on the computer), and maybe an hour a week later on. I was able to sort the information any way I wanted, and I printed it and put it all into a three-ring binder. My cover driver loved it, because all the directions were heading out from the center of the route and I made them as simple as possible. And yes, I also put alternate delivery info in.
My center manager saw it once, and asked if I could put a book together for other rural routes. I told him very simply that he couldn't afford it.