Forts are kind of a double-edged sword. They're very hard to crack, but if they get captured by an AI stack of doom and were used to get resources, then that is a huge blow as now you've lost them to your rivals, and it may take a while before you get it back. You want them on strategic points to maximize XP gain and make progressively harder to crack the more troops the AI flings at it, but do not use them to collect resources for the Kuriotates just for the possibility of losing control of it.
This is where using Settlements to collect resources over Forts shines, because Settlements in my experience just get razed upon capture which means your rivals won't get the resources. This makes reclaiming the lost resources by replacing the Settlement so much easier and cost effective compared to trying to recapture a Fort.