Yes, getting students to relax is important, and also being totally clear on where their fingers must move from chord to chord is critical. There should be no adjusting of fingers after they land on the frets to form a chord.

Also check this out: http://www.cyberfret.com/teachers-teaching/tom-hess/teaching-chords-to-beginning-guitar-students/index.php

This lesson talks about the exact topic you are asking about pretty well.