I think that maybe 1 FF per leg is WAY to expensive. But, for example, 4 FF is good.
I'm playing in a Sam's game, and it is just great to have 4 FF. You don't need to go for it, but if you want, and you're not the first one to go for it, then BAD LUCK! Try again at the next FF. And, of course, make sure you're not eliminated and that you're in the first placings in case there's another one soon!