I believe it was. With so many different cards to cover in the article, going by set kept me on track while writing as opposed to cherry picking random cards that would rotate.
At the risk of sounding overly critical, I'm not sure how well you stayed "on track" in the first place. There were a few inclusions I found questionable, more so due to what was not included. Of course, when composing your list of cards to comment upon, nothing says it can't be compiled according to set. When writing about it, though, a more topical approach helps you stay on topic while recognizing what cards are available multiple times and address more general concepts, like Ace Specs disappearing. Granted I also thought more Ace Spec cards were worth discussing; that may explain my bias.
Also, I might be doing a part two to this article. One that talks about the format post-rotation, and how specific cards get better/worse in XY-On.
Which according to what I have been saying, should be more like part seven.
Still I look forward to reading it and thank you for explaining why you chose the approach you did. You made many good and accurate points.