The thing about participating in a FATE is that even a failure will net experience/GC seals/gil as long as you contributed. You may not get as much as a full success, but pretty close to it. If you're forced to level via the FATE system instead of in dungeons (Ninja's will know this all too well), FATE hopping is generally the most efficient means of accumulating experience points (especially if there aren't a lot of people around) and taking the failure exp of several FATE encounters as opposed to the success exp of one encounter.