Atma drop rate?

[Exstal]

I started recording exactly how much time it takes me to get my Atma (my last 7 on my SCH took 19 hours, 21 minutes). The way I'm recording is I set the time I start and count all the time in between, hitting every single fate I can make it to. That means watching the map like hawk. I'll update when I finish collecting the next 10 for Ninja Atma (currently at 2/12 with 1h43m elapsed).

Finally finished　regrinding all Atma;
Total Time: 22h18m
Total fates: 361+*

*Forgot to record number of fates for first two.