

It actually works pretty well by chance more than anything else. 1000 ft is a really good altitude separation between aircraft. 500 is a good offset for irregular traffic too. Multiples of 150/300 m are more annoying to work with and 500/1000 m would waste an excessively large amount of airspace.
I tried to give my mom a pihole, she made me get rid of it because it broke the NY times and some rando mobile game she plays. Some people can’t be helped.