it depend, it seem there is point that can be block and some other not (main gate they always respawn or u need to kill really a lot to make stop spawn, when i first tried main gate with 10thralls after something like 400+kills it has stopped at first gate), and seem also that the difficulty can vary at each generation of fortress, but i still explore to discover so cannot explain all.

i play on official only so no mods, simply the actual version.

they made it more diifcult than on test version, more npc points.

but on side of castle there is less npc, main gate is the strong point that npc defend