Interesting practice, it reminds me a little of the complex visualisation accompanying the mantra, described in the John Blofeld book:
https://www.amazon.co.uk/Bodhisattva-Compassion-Mystical-Tradition-Shambhala/dp/1590307356
I'm always fascinated by the practices that emerge around the six word mantra. It seems one of the most powerful, transformative prayers available to layperson.
My own practice with this mantra is slightly less esoteric. I do a modified version of a visualisation from a book called 'Wheel of Great Compassion' by Lorne Ladner.
I use a prayer wheel alongside the recitation, and I visualise the light from the wheel healing and blessing beings of each of the six realms in turn.
For me, the mani is a vehicle for awakening bodhicitta. It uplifts my mind, and ensures that my main meditation practice is on the right path. But more than that, I believe it actually has an effect in benefitting beings in samsara.
