Before GPS, there were mapping programs. When I went into coverage after being on two routes for 20+ years, I had to learn a lot of routes.
What you learn to do is sectionalize the area. On most areas the breaks are pretty obvious. And you run those sections one at a time. I would print pages for each section that were large enough to read, and inserted break numbers where needed. That really helped. I also got an updated copy every year of the 911 directory, that has all the street names for each of the counties I delivered. IT would have the name of the street, city, then directions from well known streets or landmarks. That really helped for those hard to find streets. And once computerized, I was able to update it with any new streets that were built and named, many before the first house was built.
I also used this this system when I driver trained as well. Most drivers appriciated the detailed maps.
There is also one neat thing about what the poster asked as well. 90% of the packages go to 1 % of the houses, or maybe 5%. You learn where these 5% are, and the rest you can count down or up from.
Couple that with what Charley posted, along with experience, and you have why we can find you without a problem.
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