For me, if I want to go for breadth (quantity), AI is fine. For depth (quality), I have to come up with it or commission someone really skilled at their work.
I take Elder Scrolls II: Daggerfall as an example. The massive scale of its world map was ultimately procedurally-generated (i.e. AI). The locations important to the main quest was hand-crafted and generally of better quality.
Grammar checking my properly written-up Wiki entries from notes of my Obsidian vault. Or finding names and acronyms, but I prefer to do that myself if possible.
To get a scale like that, I would just leave it up to extrapolation of the fundamental traits of your world. If my world was scorched, but I only write about a couple cities, you can imagine everything inbetween is a fiery hellscape too.
It’s your universe, not AI’s nor a professional’s. Try to do as much as you can by yourself, if the world your building fits with you as a person, this should be easier than it sounds.
P.S - Proc-gen is not necesserily AI, but an algorithm. A set of rules to follow with given aguments for variation. This is why games such as No Man’s Sky, that heavily use proc-gen, end up with repeating landscapes or planets. The algorithm was given similar arguments. AI is far more complex however, closer to how a biological brain determines something.
