It can be frustrating. I started in October, did 25+ battles a day and just got my first girl drop two nights ago. Then two more girls dropped for me last night. Its all RNG and it seems to be a better rate with this xmas event going on.

I was thinking the other day before I got Winter Agate that they should implement it so each battle without a girl drop would raise the probability by .01 to .03 on the next battle. that way after a few hundred battles your chances of a drop are good.