In India, it is used at celebrations like weddings and other special occasions which are traditionally associated with transcendence and transformation. It is used for worship and work but not for the sake of vanity.
It is traditional for the bride to get together with her friends and have them spend hours applying the henna to her skin and give her marriage advice in tandem.
The patterns used for weddings are much more intricate and time consuming (than the everyday wear) and therefore the brides friends have lots of time to give her advice on erotic activities for her wedding night, sexual pointers and tips during the hours that it can take to complete the design. The brides henna must be more beautiful and intricate than anyone elses of course since it is, after all, her special day.