Why is 7 the magic number? Are 6 genuinely too few and is 8 definitely too much. As a kid I remember getting a 9 ply board - it was the advertised selling point of the board. I don't recall the brand any more or anything about the board at all to be honest aside from this detail. I was hyped 'cause i was like, 'oh cool, this is a special, extra strong board, how radical' - but i wasn't snapping boards then and still am not really ever snapping boards.
I also remember those almost boards early on that were like 100 ply going across the board instead of stacked on top of each other. Never had one or saw one in the flesh.
Rambling at this point, but yeah, how bad could a 6 ply board be? (or just whatever, anything tangentially related to this question/idea)