I have 6 atmas so far.

Got all of them using Party Finder.

First one was a pain and took like 4 hours (2h at one day + 2h on the next day).
2nd one took like 1 hour and a half, all the others less than 20 minutes.

I've seen that healers that join a fate party late and spam Succor/Medica (even when there is absolutely no need to) seem to get Atmas real quick and leave the party.
Haven't tried that though with my WHM yet.

I've noticed that on really low level fates, where DPS can one or two shot pretty much everything, it's usually the DPS that wins the atma and leaves the party.
(As a tank I can barely damage or aggro mobs, they are gone way too fast. I'm on PS3 btw)

With Warrior, I got 4 of my atmas on boss fights (with or without adds) or strong-ish fate mobs.


I used tanks buffs even when there is no need to, flashed and overpowered the hell out of everything till I'm out of TP and MP and focused on killing the few regular mobs that are NOT part of the fate that I AoE aggroed, instead of focusing on fate mobs that the DPS are smashing.
It may be a coincidence, but it worked for me 4 times now and it happened on the 2nd / 3rd / 4th fate of the area in less than 20 minutes and I could leave the PF party >D