If the prevailing form of transportation is ox cart, then settlements tend to spread out to about 8 miles apart. And if your prevailing form of transportation is horse drawn carriage at the time the region is first settled, then they tend to spread out again to about 20 miles apart.
In farmable land, people are going to want to farm all, or at least most, of the land - some areas may be kept 'waste' for firewood and livestock, but much will be arable. In the absence of mechanised agriculture, farmers will not want to travel 10 miles to their fields; around 3 miles/1 league/1 hour's walk is a practical maximum in most cases; this might be pushed a bit in extremely dangerous frontier territory where farmers cluster in walled towns at night & travel during the day, but I think it's a good rule of thumb: practically speaking, in farmable land you are very unlikely to see settlements more than about 6 miles apart.
For a 12-mile hex you will thus encounter at minimum 2 villages while crossing the hex. More typically would be 1 village per 2 miles, or 6 across the hex. If the whole hex is farmland around 30 villages in the hex would be typical for good land; as few as 7 or 8 in rugged, poor farmland.
Here's a 1575 map of Suffolk, an area of mstly good, rolling farmland:
http://www.foxearth.org.uk/Maps/firstPrintedSuffolkMap1575.jpg
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