I'm not really accumulating GF. But as they come out, I keep them for the time being. They may be useful in Survival, or, as it was the case with very few from the former set, I was able to max them, and burn the RF instead. But now, things are more complicated, because Survival needs more cards, while to max out the set I will probably need to burn some of the GF and doubles toward the end. It won't be easy to decide what will be better to do.