They would like to have healing be a treatment like massage, which one can apply at will for a deliberately determined length of time, in a regular, controlled manner. Healing simply is not like that. It seems to occur when a certain complex of conditions are present, but we have yet to identify all of the relevant factors. Probably, even if we succeed in identifying most or all of them, we shall still have difficulty controlling many of them. Healing is a state of being in which one's mind is centred, or focused, on the intent to help another person.
Healing involves an unconditionally accepting, loving awareness of the person one is with.
It brings one to feel one is part of a larger 'whole' - a cosmic, transpersonal awareness. It is the latter which gives healing the label, 'spiritual' healing. One cannot be a psychiatrist and not question oneself when one has such experiences. And so on. At times like those I fall back on my knowledge of the impressive research evidence for the effects of healing.