I hope I am understanding what you mean by this post, ill just share the way I use knowledge of shamanism in my practice. I personally have taken the knowledge that I learned in the Peruvian Shamans, and I apply it to my changa use. I make by changa batches vine heavy with a 20x ayahuasca vine/leaf that soaks for a whole full moon cycle. I have a white blend, a yellow blend, and a black blend in order of strength(or more so just the white and yellow are more gentle, and the black is for the serious work). I use mapachos to bless everything, and have a mesa I've developed over the last 2 years now that is crucial to my ceremonies. I will post pictures tomorrow
My dosage with change is never weighed, I just always go with my feeling on how much should go in the bowl. Sometimes I will just load it extra full for a prolonged journey.
My current setting is in a small patch of redwoods on the property that I'm on, it has a very sacred energy to me. I actually intend to make a tree blend soon using some bark from one of the trees, with their permission of course. I would like to add other trees as well to the blend such as either mimosa hostilis, acacia, or Palo Santo, but that's to come later down the rode.
My intention with my journeys varies greatly, but usually when its not a specific intention I just ask mother Ayahuasca to clean what needs to be cleaned, heal what needs to be healed, and teach what needs to be taught. A simply but very effective request.
Its hard for me to exactly answer you question because I have no idea what the mind of schizophrenia is like. However there have been many of times with the sacred plants that I've told myself "this must be what its like to be schizophrenic". I will share this link though because if you haven't read it, it may give you a very good answer
What a shaman sees in a mental hospitalHope I passed