Counter rotation is not generally a first choice transition.  It's labor intensive and movement inefficient.  It's a common transition technique of the lesser skilled skier who habitually pivots their skis to begin there turn.   In developing good skiers, the elimination of that pivot is a first order of business issue.  In doing that, any counter rotation present needs to be discarded.  

Later when teaching learning to pivot efficiently, for those times a pivot is authentically needed, anticipation is taught as a better way of executing it.  Anticipation is the manner in which good skiers generally perform a start of the turn pivot.  

That said, there will be special instances when counter rotation may still be uses.  If a pivot is suddenly needed, but the preparations have not been made to use anticipation, counter rotation is always at hand to as a fill in technique.  And sometimes when speeds are very slow, a little assistance is needed to get the skis pivoted quickly, beyond what anticipation power can do alone.  Here too, a little counter rotation is a perfectly acceptable helper. 

One of the important reasons for practicing counter rotation is simply to use it as a contrast sensory experience.  When you can feel the difference between counter rotation, and anticipation, you'll from that point on know immediately which one you're using as you pivot.  With that level of awareness, you can easily adjust your technique to conform to your desired form of execution.