Hi Kathrin,
Great question. I did that to focus on the technique of one side at a time. Sometimes you may choose to do a twist on one side only or even it out by taking it over to the other side. Very often in Arabic Raqs Sharqi style you will see a traveling twist where the emphasis stay on one side. When drilling it is nice to build dexterity by drilling both side. Either way is acceptable.Thanks for the great question!
Replied on Twists
07 Jan 22:58
And here you can see that one sided accent in a more advanced variation:https://raqsonline.com/programs/quarter-twist-shimmy