What's wrong with the Duty Finder?

[Naruke]

I mean... is it broken? It's 6 days in a row (and I'm not joking) that in Duty Roulette Level 60 Dungeons it comes out The Aetherochemical Research Facility meanwhile, in that Roulette, can come out:
-The Aetherochemical Research Facility
-Neverreap
-The Fractal Continuum
-Saint Mocianne's Arboretum
-Pharos Sirius (Hard)
The % that can come out only 1 of those 6 days in a row is really low so... can you just do something that I don't have to do always the same dungeon everyday? (a remember trigger or I don't know).
The game is just like farm, farm, farm and farm.. ok I see that farming is something like "doing everytime/everyday the same stuff" but not always the same dungeon if there are 5 choise.

EDIT: Oh yes... Roulette Level 50 same stuff with The Keeper of the Lake.. and I don't have to list what Dungeon can come out right?