My character has become duke of Flanders, holding all six counties personally (which I intend to keep through the game, making Flanders into centre of power for the dynasty). What is the meta nowadays with regards to provincial development? Does one still want to fill the counties with cities for all the money, is a mix of castles and cities viable and plausible? Should the duke keep all six counties under direct rule or keep just Brugge for himself and fill it with castles for all the levies? Or maybe a different strategy altogether?
Here's my approach (in order of importance):
1. Stack everything in the capital county:
--- Personally own as many castles as possible
--- Build the "great walls" great work there (gives +base levies to each castle)
--- Station your marshal and steward there (gives +x% levies and +y% personal income)
--- Push prosperity until you have all the permanent county modifiers (ie. more juicy +x% modifiers)
--- Build the awesomest hospital (preserves prosperity, boosts tech gain, non-black-death epidemics might never affect your court)
--- Get one of the bloodlines that permits
city infrastructure buildings (the only way to get 100% disease resistance)
2. Personally own the county capital in all other counties in your capital duchy.
--- Build decent hospitals in these counties - they probably surround the capital and decent hospitals can sometimes prevent epidemics from bordering your capital.
3. Personally own 1-2 random counties in useful places (eg. silk road trade posts, pagan holy sites for easy conversion, border counties to block vassal expansion).
4. Personally own 1-2 extra baronies in your capital duchy (eg. for cheesing artifact inheritance, claim wars, etc)
5. Fill all other holdings in your capital duchy with cities (because cash is probably more useful than vassal levies)
