Eventually you'll get it. That's the whole idea behind it. I did over 1300 FATES before i got mine. It doesnt matter what system they implement, you're going to have to grind and spend time.
It's not like you're going to end up not getting it. Everyone will, eventually.

Best advice i can give you is to just change area's once in a while. That aways seemed (placebo effect perhaps) to help for me.


Start out in an area with fates that can be completed <2 minutes. Save the harder area's for last and team up with others (through the Party Finder) if they pop up to breeze through them instead of spending a lot of time.