I was in my 20s before I realized even numbered houses are always on one side of the street and odd numbers on the other. Literally no excuse for not figuring that out.
I "knew" this and a had a really good friend who did not. Both of us grew up in the same area, and we met in school, so you'd expect we should agree on this, right?
While "arguing" about it one day, it turns out the suburb they'd grown up in had several private subdivisions where the builders could do whatever they wanted. Houses were numbered sequentially following one direction of the private street, then the other. So the house nearest the entrance of the subdivision would be "100 Maple Street" and across the street would be "143 Maple Street".
Because they'd grown up mainly going to other friends' houses in the private subdivisions, my house address was the odd one and theirs were normal to them.
In the UK, oh wow, you will encounter some weird numbering issues. I live on the corner of a street in a very complex, 400 year old area, and I am forever leaning out of the window to shout instructions to utterly bemused couriers.
Also on older estates where spare green spaces have been used up by additional houses so you end up with 21,23,25,25A, 25B.
The UK can be weird....
And if you live in some regularly redeveloped bit of a town that grew in the Georgian era you can end up with clusters of houses that have almost no discernible pattern left over; I live in such a house. The naming around here is astonishingly complex, such that if I explain it too much I would identify where I live.
(I have three physical neighbours -- that is, I share walls with them. And we are on three different roads, legally speaking)
The plus side is that as you get to know the couriers who you've helped, you begin to understand that your packages will never go missing. There is an Amazon driver who smiles from ear-to-ear when he delivers for me, and I even get good service from Evri.
I move soon, and since I'm the only person here who works from home who has a clear view of where all the delivery drivers get out of their vehicles wearing a confused look, I expect parcel delivery accuracy to drop for my neighbours when I'm gone.
Somewhat useful for couriers, since a large number of houses are neither numbered or named, but the post office will know who lives where. I say somewhat, because they will often not use it when it's given.
The rule, ~if I remember correctly (and matches my experience)~ confirmed by Googling is:
1) distance in meters from the beginning of the street to the start of the terrain where the building is in;
2)rounded to even number on the lefthand side and to odd number on the righthand side of the street/road
I guess knowing the rule isn useful so you know if you are at Soandso st. 200 and yout destination is Soandso st. 2200 thats a 2km walk there
The rule is that moving away from the post office, the left and right are predictably odd or even.
The other popular rule is that say the north side of an east-west st is odd etc.
Neither of these are followed carefully these days.