You mean, why does the second yak come from a different direction each round? Because submissions give a random seed each time. Yaks that come from one direction might come from another.
I think what’s happening is that your hero can see the previous yaks because they are not completely fenced off.
I believe the original instructions were to build the fence 10 meters above or below a yak’s position, not in relation to your hero’s position. (If you want the position to be in relation to your hero’s position, I think it’s by 5 meters.)