I've dual-boxed full clear of the zone a bunch of times recently on MNK+WHM mule(roughly 20min clear time), THF+WHM (a bit tighter on time). Soloed it on DNC. Delve boss weapons and good Adoulin gear. I'm sure other DD+healer combos or self-sufficient solo jobs could also at the very least clear a couple NMs in a 30min run, if not get the win in 30min.
Since each cluster of 10 mobs + 1 NM is in their own area, you don't even have to clear the whole floor to try for the item you want.
Drop rate on any of the items does kinda suck and there is a good chance you'd spend less overall time just farming other stuff for gil to buy the sash on the AH. But if you're feeling especially lucky or just enjoy Limbus, go for it. Personally, I've just always really liked Limbus so I did this zone most days for a few weeks for fun. Wasn't really keeping count of how many times I went, but in maybe a dozen or so runs I managed 2x Prodigious Mantle, 1x Sortiarius Earring, and 1x Patentia Sash.
There's some cost invovled in going since the key item costs 75 ABCs (plus 15k per character for soap), but you can make most of that back with ABC drops in the run. On MNK/WAR I would generally end up with 60-something ABCs for a full clear, on THF was usually low 70s almost breaking even. TH does affect coin drops from normal mobs, but NOT chest drops (each NM drops a chest with ABCs plus a chance at their item).
So, if you're really looking at it from a cost/time efficiency perspective you may well be better off farming other stuff. In my case I'll assume I did 14 runs (12 CS II and a couple runs of normal Limbus zones to farm up some ABCs for entry items) and ended up getting item drops worth roughly 5.5 million on my server. Subtract 30k per run dual-boxing for soap (420,000 total) and you're looking at about 5 million gil worth of drops. Time spent was roughly 10 hours (at about 40-45 min per run to go get soap, tele to Sea and run to Apollyon, and do the zone), so about 500k/hour profit. I'm sure I could have done better farming more profitable things. Of course, luck on drops plays into it, as does whether you just enjoy the event like I do.
Strategies specific to the mobs:
- The 10 normal mobs of each family do not link with each other or the NMs, but do have a fairly big aggro range and if you're not careful you can aggro multiples.
- I generally prefer aggro pulling 2-3 mobs at once just to speed things up, they really aren't that hard.
- Tauri are stupid easy, and the NM drops the sash (most valuable drop). I always did this set first.
- Ahriman are by far the most annoying mob family (sleep, -ga spells, occasional SMN Astral Flow if they bother to summon a pet, unless you can silence they sit there and cast instead of come right to you on pull). The NM kinda sucks with 1-shot potential from Deathly Glare or casting Death, a strong Chainspell+nukes, Breakga. Be on your toes or you might actually die on this one (I settled into a routine using MNK where I'd 1hour it just for some extra assurance). Can still recover from a wipe and clear the zone if you can kill fast enough, I've done it more than once. NM drops the second most valuable item (earring), which is the main reason you might not want to save this group for last if you're not completely confident you can full clear the zone in the 30min time limit. But if you screw it up and die, you're really up against the clock to get through the zone and get as many ABC drops + item chances as you can.
- Demons are not hard, but can be moderately annoying - PLDs using Invincible, Sleepga from mages, etc. NM drops the least valuable item (mantle), so you may want to save this for the last group if you're trying to maximize chances to get money drops.
Good luck!