As far as i am aware the spawns are random with a chance to have 1 or 2 star variants.

The mobs once spawned in again, as far as i'm aware, do not despawn until they have been killed. I've come across deer, pigs, necks and other things that i'd hit like once and they were still around that area hours later.

It might be a case of if you don't find a 1/2 star wolf in a pack, wiping them out and leaving the area to let them respawn is a good idea? it worked for me and the pigs.