If you do the marks first you get economizer from one of the elite marks which reduces mp costs by 80% helps with farming a lot, one of the bosses also has a eidolon dress you can steal for vera, which reduces mp costs by 40% iirc.
Overall this is a good farming location, but like you said is slow, sadly there is no easy way to farm a bunch of shards fast and call it a day, thanks to shards and golden apples being so expensive to buy.