Just to clarify as I didn't quite get your wording, only certain jobs share some of the sets, so Healers, Casters and Ranged DPS are easiest to save up for. All the melee and tanks have their own unique sets that cannot be worn by other jobs in the same category so those ones take a little longer to compete.
*Didn't include SAM and RDM as they were added after SB, but obviously they can share MNK and caster gear.