I took this on casually. For me, as it couldn't hurt, I did the theorized, unRNG-the-RNG-because-it-worked-for-some people way, and only farmed the areas that coincided with the JP clock method approach, because, well, some say it worked wonders for them. It's still RNG. And it is still luck.
But I refused to farm for Atmas more than 2 hours at any given time, unless I got an Atma in those two hours, and even then, only on weekends (as I only log in for an hour or so at night). Farming for Atmas for hours and hours on end - I ain't got time for dat!
All joking aside, I probably spent about 30 hours to get all of mine, plus two duplicates. Do I think the drop rate is abysmal? Compared to the minion Opo thing, no (I have yet to see this drop in any runs I have done, and do at least 15 - 20 a week since release). Compared to raptor skin, yes. Compared to the DF chance of clearing Titan Ex with no preset party? No.
I personally think you are wasting your time doing more than 4 hours a day, unless you are getting an Atma every four hours. And I personally think you shouldn't stay in a region more than an hour, two at most. Even though I mentioned I wouldn't stay longer than 2 hours in a region, to be honest, it was probably no longer than 45 minutes, an hour at most. And there were DF dungeon runs in between, and I used either my PLD, WHM or BLM while running those FATEs. And got Atma drops using all 3.
BUT I outright refused to focus on it. For those that did and were successful, congrats!!! But for me, it was just in between everything else for the most part. (And to show you pure RNG power - an LS bud of mine farmed a region for 5 hours before I came in to try for one. I got my first one in 3 FATEs, and continued to help him, and got a duplicate 2 FATEs later. He still didn't get one for the rest of the day, while I went some where else and got one. Then not another for the rest of the week)