There were already many recent discussions about the usefulness of the different fortresses, but I just rediscovered something that bugs me with castles of all types. It might have been discussed before, but I could not find where:
My situation: There's a chokepoint on the shady rim which I wish to merely defend against Baphomet (AI). Hence I bought myself some province defense and added a mage to boost them. This cheap defense worked well so far, but soon more than one mage will be required to secure that province. Mages are expensive, so before they bore themselves to death doing nothing but patrolling, I thought to myself that I should build a lab there so that they can busy themselves while not actively defending the province. This is cute: with nothing but a lab, the mages garrisoned there double as active researchers and as active defenders at the same time!
However, once I invested in a lab, I want to make the most of my investment and use the lab to build more mages. However, the locals are pretty dumb, so I cannot recruit mages unless I also build a fortress there. If I were to invest in an expensive fortress, my mages could not research anymore, as they must be set to patrol in order to boost the PD, for otherwise they would merely hide in their labs when the hapless PD gets slaughtered.

With the PD being useless, I need to garrison non-upkeep-free troops there to defend the castle, making the whole thing superfluous (i.e. securing the choke point with the least expenses, as money is scarce on the shady rim and I really need to attack Baphomet (AI) on the main front).
I know that it all makes sense somehow game-wise, but I really feel that it is somehow wrong that building a castle is actually disadvantageous! Why does the presence of the castle prevent my mages do perform the feats they could do before???
