I agree this is definitely a good innovation, but you can still blow through all that materia on one item, because RNG.
While it does alleviate some of the strain, there are a lot of FCs with a large number of members. If we use the example above 100 melds per item with one set of full 2 star gear = 12 items = 1200 materia/200 per voyage * 30 hours = 180 hours or 7.5 days = per full set, per member (obviously belt and acc only need melds once)
But we can see how the system is a bit punishing,keep in mind you could meld one piece with five materia if Rngesus is on your side. :)
