SWIM goes back and forth on this issue. It may come down to a difference between pure spice and changa.
She went too far too many times when starting out, and habituated a panic response to the spice. Once she figured out the proper dose, she very much preferred to blast straight through, as all of her anxiety symptoms disappeared as soon as breaking through. Sub-breakthrough doses only increased the discomfort.
After one amazing experience with changa, and one that took her too far, she decided to go very slowly her third time. Seeing the amount of spice crystals hanging off the changa also influenced this decision. She went so slowly that she did not break through the entire time. She also had all of her anxiety dissolved by the carrier wave; it moved through her body, finding the points of anxiety and dissolving them with its vibrations. After all the points of anxiety dissolved, the most amazing sensations of loving warmth flowed through all of her muscles. Last night she tried out the same thing, to find out if the healing continued. Again, she had a very physical journey, but with a great feeling of well-being throughout. When she tried to breakthrough, with a new load of changa, she smoked it and hyperspace indicated this was not the time and *reduced* the effects of the spice.
These low doses have had very positive effects in her daily life after going through them. She would especially emphasize the role of the carrier-wave building to near breakthrough but not quite making it.
SWIM also admits that after going too, too far with the changa her second time, she may have some unconscious fear of going back immediately, but that does not change the positive aspect of these recent journeys.
Another random thought: years ago, I did many journeys with IM injections of ketamine. So many healthy changes happened inside my mind, and I felt like life had changed completely. Soon though, my body began rejecting these new realities. I went on to do lots of work with rue & mimosa, mushrooms and LSD. These journeys all focused on body work, and ultimately brought my reality into alignment with the changes I had made using ketamine. Due to this, I came to the conclusion that self-work which doesn't directly impact the body has much less of a long-term impact that those that do.
PK Dick is to LSD as HP Lovecraft is to Mushrooms