@AMASH my reasoning goes a little like this.
ST1 has a lot of energy and spiritual cleansing/healing, plus manifestation of the best spiritual path. So for me Sex Masteryx2 is the perfect complement due to its sexual healing, being sexual energy so important in the development of higher consciousness.
ST2 works for the development of spiritual/energetic skills you already have, and the learning of new ones. So Limitless fits this by enhancing learning processes.
About ST3
The third stage, the stage of Awakening, focuses on awakening your spiritual reality and potential. With Awakening, you will no longer be skeptical of spirituality – you will know it and live it.
With that comes great power, with great power sometimes its easy to become abusive or to be manipulated to use it for negative purposes.
I feel PCC will strenghten my ability to recognize the way power its being used and to be further shielded from negativity and manipulation, and of course to not doit yourself.