I've been wondering about the population in settlements -- concentrated populations -- versus the spread out population.
In Washington State, we have large areas of sparse population, in the forested mountainous areas. In these areas, I often see fairly isolated homesteads -- a half dozen buildings clustered together in a farm or logging/hunting/road services set up -- without even a "thorp" per se. That is, it's an isolated family homestead, not a collection of families living together.
I'm also thinking about Westerns, like "The Searchers", where each ranch seems to be isolated from the others, it's own little fortified homestead and outbuildings, with one farm family and maybe some ranchhands. (If you haven't seen it, the opening scenes at Luke's Uncle's moisture farm in Star Wars are an indirect ripoff of the Searchers -- the discovery of the tracks, spears in the sand, and then bodies at the burned homestead being a DIRECT homage.)
I think you'd also see stuff like that in the highlands or borderlands of medieval Scotland, etc.
Since D&D is often in the 'Borderlands', I wonder how many folks should be in a settlement -- a place with a name and several families -- versus a croft?
For my campaign, I'm thinking a ratio of about 6-7 "rural" folks to 1 in a named significant settlement. So, for example, Keep on the Borderlands has a population of 200-250 safe behind its thick and expensive walls, but I'm setting the population of the region at 1500, with only one other named settlement (a ferry crossing and walled inn with some homes clustering around it). The rest of the 1500 would be homesteads, crofts, semi-nomadic herdsmen, trappers, mountain men, etc.
On Wikipedia, I found that the current day British definition of "rural area" is a region where < 26% of the population lives in a "market town". I'm thinking D&D world should be overwhelmingly rural, so at least a 4:1 ratio of "rural" to "town" folk.
Rural area - Wikipedia, the free encyclopedia