Here’s a post for people trying to sort this stuff out. A pretty detailed description of how the system works and changes from the previous (far more vague) chunk-and-prestige based system that could also merge settlements that didn’t … exactly touch.
For me once I understood how the server breaks the world apart it made a lot of things easier to deal with in game, anyways. It’s worth understanding the breakdown of chunks/plot columns/plots.
The earliest stuff references a 9 plots in 9 columns rule that was quickly replaced with the 6 plots in 9 columns rule I put above:
So, regen and respawns, as well as creature spawn and some other “world” features are handled in chunks.
The settlement system and the compactness system are handled in plot columns.
Actual control of the space is taken on a per-plot basis.
For your amusement here’s Luca trying to explain the changes to the new system without explaining plot columns first:
I can tell you pretty confidently though there have been no significant changes to the way this system works since that time. Newer systems for plot protection/reservation and compactness have been put over the top of it in layers that continue to analyse the relationships as primarily a grid of plot columns.