This was a good article. A nice tangent from monster description and into PCs as wandering monsters. It finally brought the DM's map back to the game by showing how they can be grasped from our own experiences.
For me, most published campaign settings are gonzo-sized. Far outsized for how the distribution of medieval territories spread based on necessities like food, defense, and safe transport speeds. Most folks lived within 1 mile of their birthplace their whole lives for good reason.
The 3 map sizes suggested should not be game requirements IMO. So much about the map the PCs explore is its high detail near the starting location, but vast scalability throughout. The overland map zooms in to the same map holding every page of dungeon map, battle map, and even creature/item maps needed.
Here's an example of how I might start these:[sblock]Think: Migration Patterns.
1st, the multiverse, plane, planet creation, along with solids, liquids, gases, gravity, and other near constants within the standard campaign timeline - human coming of age to old age basically.
2nd, Surface creation with plate creation, tectonic movement with vertical terrain, liquid distribution and cycling, which ties into atmosphere causing land erosion, climate zones, and terrain types.
3rd, Population migration, most likely starting with vegetation, then insects and animals.
4th, Monster territory creation on the local scale map taking into account previously determined elements like terrain, climate, food sources, and other life necessities on the larger map. Types of territory and lairs, self-constructed or otherwise, are by creature alignment, culture and technology. This step determines your campaign dungeon level zones for the wilderness as well as mass lair locations like cities and the proverbial dungeons. Humans typically set up shop in the plains, but are traditionally in D&D the most open to adaptation (demi-human means human-kin after all).
5th, PC starting location and starting adventures occur in level 1 zones, traditionally in the borderlands. Places on the edge of civilization the PCs lawfully defend and search out and delve into the dungeons of scary monsters opposed to them.
For human culture we can steal for medieval or medieval-similar cultures of our own past. We don't have to stick with Europe, but those towns are usually one wagon's ride away from the next and never far from a defensible fortification. Farming methods help determine arable land acreage needed to support number of population yearly. Hunting and gathering cultures are going to be much, much smaller. Defenses not only require everyone nearby to be able to reach them quickly, but are expensive to build and maintain. Think the mott and bailey in Hommlet. It's right in town and still growing. Someone's old, fallen in moathouse is where the monsters have crept into after its abandoning.
Last thing, old wargames used 30 or 24 mile hexes because they were close to human movement in a day without a forced march causing fatigue. I think there were probably wargamer adherents in both camps, but largely these numbers were due to their large number of divisors, wargames uses fractions for speed. 30 has 1/2, 1/3, 1/5, 1/6, 1/10, 1/15. 24 1/2, 1/3, 1/4, 1/6, 1/8, 1/12. I don't personally uses hexes except for quick overlays to measure PCs moving off road. I mean, it's so easy to pre-measure the lines on the map for distance and things like size volume after creation. And these things can be rated too. --Oh, and also measures should be whatever is easiest for a player and player group, metric or imperial.[/sblock]The big take away here is: Rules should reference the map, the game board, the game's Field of Play.
For instance, Teleport has a mischance of 18%? Roll 1d100 for miles randomly determined from where you are casting the spell on the map. Summoning calls on "nearby animals" to help? What animals are shown to be in range? Tracking someone through the forest, but you've gotten lost? The DM has your true position on their map, and yours and the quarry's trails marked. Having a actual campaign map to explore means roaming aimlessly around might actually result in running into something hard to find - something it might have taken far more time to learn of (like Nulb).