How many fortresses to build?

[Sandman]

Sencha said:
However, the AI was still doing better comparatively, and my intelligence on their regions was low. I didn't know how many fortresses they had, but I was thinking I didn't have enough.

If you find a province which can produce scouts, make one every turn. It's not that expensive, and the info gained is invaluable.

Are you building labs in the forts and are you hiring enough mages? Generally speaking, every fort should be making one mage a turn. M Ermor mages can reanimate undead, so they pay for themselves quickly.