Agree, that a bigger wing does not mean you dont need a "medium" one.
The Carver wing is IMO the best allround size for everything
And then a bigger wing can be used as an additional wing for riding waves if you like a bigger wing for that, or practicing things, or for heavier riders.
But eventhough I find a big surf wing really fun and awesome sometimes in waves, I also pick my 790 cm2 wing very often, almost same size as the Carver, simply because it is still a relatively big wing, but gives you so much more fun allround because of its speed and lower drag, and they can ride quite slow too.
A universal wing size so to speak