Aw geez yeah I never thought of that … round yo-yo means it doesn’t matter “how far” it is screwed in, which wouldn’t be the case for a square!
Also we could put the “lots of airhole cuts in the yo-yo” into the worst category, as a design element?
http://www.highspeedyoyo.com/reviews/a-m/innovative-yo-yo-concepts/iyyc-breathe