I seem to recall that when I was a kid, we would fly on widebodies where the rows were set up "asymmetrically" as in 3-4-2 versus 3-3-3.
Is there a pro or con to either way? It seems that it's unlikely you'd find a lot of parties of 3, but couples would be happy with the section of 2 seats. Possibly families of 3 or 4.
But 3-3-3 doesn't really accommodate too many (at least not in today's world of nearly always full flights).