There is ALWAYS this problem, in ALL instances, for some pieces.
There's always some pieces that drop 90% of the time, and some other that drop less than 1% of the time.
In Coil, healer stuff seem....well i have never seen any healer gear drop. and only seen a handful of ppl wearing any, on Balmung, while drg/mnk stuff supposedly dropped like candy, from a smashed pinata.
In AK there was some accessories that i only saw drop once, in months.
Cant say i disagree with the mnk drops in CT, since i got head/body/pants/belt, within 2 runs each. Dont think i seen boots/gloves yet, but dont really care about them, aside from vanity i guess.