Holdings should take longer to develop.

[Arcvalons]

In CK2, no matter the start date, within 200 years all holding slots in a county were used and fort levels were very high, making it very time consuming and costly to siege anything. Hopefully that is better balanced this time around so it will take the full span of the game to develop counties fully.

 

[Riamus]

In CK2, no matter the start date, within 200 years all holding slots in a county were used and fort levels were very high, making it very time consuming and costly to siege anything. Hopefully that is better balanced this time around so it will take the full span of the game to develop counties fully.

It has been started in the video about counties that they are designed so that development of the county should be slow enough to take much of your game to complete. That doesn't mean a min-max game can't finish sooner, of course. As far as buildings, I don't know that there is anything to prevent making them early if you have the resources.