please:
-I stopped playing against the AI a long time ago, so the tactics were only tested against other players.
-on XL maps with dungeons, experience shows that the game rarely lasts more than 2-3 months.
-there are, of course, such maps, but they are very rare... I think it depends on the map generator or the template they are created from, I don't know for sure.
-the minimum can be almost anything, but larger ones are already a problem, and with vampires, the maximum is easily defeated without losses (a dozen skeletons don't count).