I killed in and around that house for 3 hours and didn't get a single militia skeleton.
I went to where the grass turns into sand (from Cabilis) turned to the right, and went up to the plateau where the PoK book is on Live and killed there, and got 4 'a militia skeletons' to spawn within an hour or so.
I mostly stayed near the flat ground, but I would venture into the trees to kill if I saw mobs up.