When I first took over a rural delivery area back in the early 70's it was 90% farms. Out of all the mailboxes on 4 different rural routes I bet 75% didn't have a name or number on them. This was before everyone was assigned an E911 address that had to be posted at the end of your driveway. You learned to make address cards on every person you located.
I have delivered neighborhoods with what everyone called "italian numbering". (The area was all Italians) Apparently, folks picked a number as they built the house. A house may be numbered 32 and next to it, 333, while across the street, it's 77.