Younger, when not yet affiliated with Church of Satan, I studied years Tantrayana and Zenbuddhist traditions. I don´t however see it wasted time though I always knew it´s not my thing to try to become altruistic spiritual being called Bodhisattva. I learnt many useful skills I have made to be a part of my Satanic magicians path. One of these things is Zazen, Zenbuddhist meditation where practitioner of meditation focuses their mind to reality as it is from moment to moment. In Zentradition the ultimate goal is to free oneself from suffering and experience the mystical satori, enlightenment. What can this kind of practice possibly give to Satanist. To person who avoids all kind of hypocritical spiritual practices and does her Magic and ritual purely to accomplish ones own needs and wants. Quite much I would say.
I practice daily a some kind of Satanic meditation as my purpose is to understand the nature of reality and reach more knowledge and power by this understanding. I use certain techniques, but when making my goal purely selfish it becomes in many ways to be a Satanic act in action. Magic, like I would describe it.
So when studying Magic and trying to reach more power and knowledge, I see it very much useful to study many traditions and practices objectively and adopt their best parts to myself. Magician, from my point of view, should always try to develop and go on without fear and rejection. Then one may reach the goal they want and desire.
I am not a spokesperson to Satanism, so all my views are more or less just personal thoughts and opinions. As private Satanist, who is also a member of the Church of Satan, I however believe that for reaching greater understanding it may be good to study and practice also what other traditions may teach to us as Satanists.