Cure 3 really shines on the 3rd nail wave for Ifrit ex imo. I keep medica II ticking for most of the fight since I'm generally not MP or enmity limited, but get the DPS team stacked up tightly as they move around and I can keep them topped up for each nail without having to worry about getting them blown up with the Inferno Howl debuff, and yes, I've been trying my utmost to get more use out of it. As you mention, titan EX jumps are perfect since the arena is so small. My team makes me keep medica II going to ensure we know where the egis are going though