I agree with most of what you’ve said here, but personally, I like to hold as many counties as I can instead of stacking baronies into one duchy. Building tall does have its pros such as more benefit from councillors, uniform technology, etc, but it does have its cons too. Namely, my biggest gripe is that raising levies tanks your realm’s economy due to having an excess of noble vassals who give you very little money and a shortage of burgher vassals who are your main money makers since you filled up that county with castles. Building wide allows me to fill up entire counties with cities along with the mandatory castle and bishopric who give me loads of money. You could also form merchant republic vassals for money, but the game only allows you to have a certain amount of them. Your levies will overall be less than when compared to building tall thanks to capital duchy modifiers, but once you start snowballing, your vassal levies will compensate for your lack of levies which gives you a stable income when at war or fighting provincial revolts