Training the superior or upper portion of the trapezius can not effectively be exercised by shrugging or even high pulling.

When you are shrugging, you are holding onto the bar to raise it, no matter how high you pull the bar you are still capable of extending the head with your extensors. Since there is no resistance to push against there is no overload and little development of  the superior trapezius muscles. 

When you securely stabilize the torso while holding on to something and the resistance is placed on the occiput or back of the skull the upper trapezius can extend the head and be maximally developed.

Fixating the torso during neck extension on the Pendulum 4 or 5 Way Neck augments the upper trapezius muscles.