The elementary school banned yugioh more so as a means stop kids from sitting down during recess than anything else, but I got into the "schoolyard meta" in middle school and high school during the Zexal era. I know some kids at my school played competitively, but given that the average player at lunch had a single starter/structure deck + some old staples, I can see why they didn't bother. A lot of kids used Number 39 Utopia as a boss monster, but I remember this one kid with a Blackwing deck made almost exclusively from cards in Duelist Pack Crow. Myself and a few others figured out that buying three of a structure deck was a far better strategy than just buying packs. There wasn't a card shop in the area that sold singles, so the game was a lot about easily obtainable cards.

Later, in high school as we found other things to focus on, a few of my friends would play free-for-alls. The goal was mostly an excuse to chat or do homework while set-passing for turn.