When you are able to look upon the the flowering rose and feel no lust (while maintaining an erection), only then are your ready to astral project.

It is more than mere denial. It is focused sex with an end result in mind. And it does not need to happen every copulation. In fact, most Tibetan practitioners would astral project during sex only irregularly. Opting instead to walk, learn and then write down the techniques of the sacred garden (or what people around here are calling "kama sutra" techniques, etc.)

Astral projection was an almst religious experience, and only a portion of sex.