pillagers, not spawning reinforcements, around the outpost, when raiding, it.

When I went to raid a pillager outpost, when I went to attack a pillager, I was expecting for more pillagers to spawn around the structure, but they don't spawn any reinforcements, sometimes they spawn, but in a very very slow rate.

in 1.11.0.7 according to the Minecraft wiki it said they can spawn inside the outpost as well, but they still don't spawn reinforcements.