I remembered! It's bad on many fixed maps!!!! A fixed position deprives the Swamp of a strong, generated spawn, and the initially known location of resources allows even expensive castles, such as Dungeon or Rampart, to build up well, and there are often few castles, no Swamps, no Pandors, which means difficulties in obtaining Swamp units of levels 4 and 5.
The speed of the fastest unit – the Dragonfly – is only surpassed by the units of the Tower and Stronghold, which means the first turn in the final battle will not be in our favor.
You can play Fortress on fixed maps, but it's often difficult. But on random maps, on the contrary, it's easy and enjoyable.