Hrm. My opinion is that complete accuracy isn't all that fun. Folks have used tax records to do analysis of, say, how many farmers it takes in a village for a blacksmith to be present, and so on and so forth. It was a lot more than you might imagine. On the other hand, looking at the D&D 3.5 Dungeon Masters Guide 2 , they have finally fleshed out Saltmarsh. Bizarrely, a town of less than four thousand people actually…
Bizarrely, a town of less than four thousand people actually has an assassins' guild, with roughly ten members. Do they take turns, each assassinating one person a year? The charitable interpretation might be that, in addition to being responsible for assassinations in the town, the guild is also responsible for assassinations in the surrounding countryside; in medieval times the rural population significantly outnum…
Introducing magic, or any kind of efficient machine or analog for modern medicine that might appear as magic in a fantasy setting means you get to throw out most of the rules that are learned from historical observations, except where you base those lessons learned on post-industrial revolution studies where the availability of electricity and modern industrial tools haven't been made readily available to developing communities and countries.