Flaming Crush tends to outdamage and be more consistent than both Ramuh and Garuda on easy prey and too weak monsters, from my experience, while sometimes not faring as well against stronger targets. Flaming Crush is just weird that way. Go farm skeletons in Gustav tunnel and reduce them to 10% HP in one crush, or spiders in Kuftal Tunnel and consistently reduce them to 1% HP with a crush or even kill them if you already tapped them a little, or of course, qutrubs, which flaming crush can hit for over 10K (see bog body in abyssea and Moshdahn in Caedarva Mire).

If you're getting bad results, get some empyrean +1/2 and 400+ summoning skill, then try.