Excellent choice of flexibility exercise. Weather it is needed or not is up to the trainer to decide. Flexibility is a very complex subject that we don't have all the knowledge about. Anyway. This particular one is great for getting that spiral line a little stretch. We usually use the AIS versio which is done in reps:
In top position (no stretch) take a deep nasal breath in, and while going into stretch gently breath out through mouth. Stretch position is hold 1-2 seconds and then up again to release the tension.
More about Active Isolated Stretching can be found on Aaron Mattes www.stretchingusa.com which really is a great source and a great method to use. Theory is based on fascia planes, muscles spindles, golgi a and much more fun. This guy actually has based his technique on human cadaver studies and empirical evidence.
We love it, but as I wrote before it's up to your expertise which method you like.
Enjoy!
Good stuff
IQspn 1 month ago