The drop rate of these style pages can be very fickle, and 5 runs is basically nothing.
We did 6 or 7 runs of CoA2 when that was on, and the style never dropped even once for any of a 4-man group, so zero masks for 25-30 completed dungeons.
I vaguely remember the drop rate being similarly awful for the Molag Kena mask.
Sacrifice an extra chicken sandwich and see if that helps!
But seriously, I wish they'd either dump the die roll from those, and switch to a token syestem... or made the drop stuff tradeable through BoE.
Or both, make the sets BoE-tradeable and make the undaunted farming not into actual gear, but "monster trophy" scraps you can then bring to some "undaunted armorer" to fashion into a helmet of your preferred weight.. far less stress for casuals this would be!