spamming castle all over feasible?

[Cainehill]

Originally posted by Master Shake:
You just have to balance things.
.... Of course, I've seen the opposite and watched people have a single fort for a 21-province empire. I prefer to pick high income provinces to progessively castle as the game progresses. It booosts income significantly from those provinces (using standard castle), and protects the province from raiders.

Yep. High income provinces, choke point provinces, high resource provinces with high resource neighbors, provinces with especially valuable magic sites. Best of all is when you can combine 2 or 3 of those attributes in one - a rich plain with a great magic site and 3 high resource neighbors, say.