^If I recall correctly, it wasn't so much the length of time to apply as it was all the glue. Plus I think she didn't believe it looked very flattering. I could be misremembering though.
She may have also had a bad reaction to the appliances. I know it was certainly a problem for the actresses that played Ko D'Ath & Na'toth
I always thought the female Minbari had a rounded crested look while the males were all rougher and spiked.
There are probably some gender differences since Lennier's has more points than Delenn's or Shaal Mayan's but it could also be part of the cultural fashion since we see how much pointier and even possibly weaponized the Warrior Caste bones are.
I'm pretty sure the more curved shape for females is a style thing, not a natural feature of Minbari sexual dimorphism. If you'll recall, there was a warrior caste female in command of the renegade ship in 'Points of Departure' and her bone was just as rough and pointy as any male Minbari we've seen.
I think Lennier's was just smoother because of his youth. Plus I think some (though by no mean all) religious caste males have a similar multi-pronged look as the warriors, but smoother and more ornately carved like Delenn's & Mayan's.
No idea where the worker caste fit into things as we very rarely ever see any of them. Probably somewhere in between.