Maybe we got too stuck on the mechanics, but it seems like wisdom/true magic solve the challenge completely, so it always makes sense for the other 2 players to folly?
Since the wisdom requires 3x the challenge value, on average you need to folly 3 times in order to wisdom so only 1/4 challenges need to be solved with big magic.
I'm probably dissecting it too much, but we hardly struck off any of our sources by the end of the 2nd chapter. Because we managed to solve most challenges with wisdom, and because the folly doesn't mechanically make it more difficult as far as I could tell.
Are we playing it wrong, did we miss a rule or should we just be doing less table talk about who has a plan?