They all are based around reducing the individuals sense of self, placing him as close to anarchy as possible, and then allowing or encouraging a particular type of mindset to arise in the person (for want of a better phrase).
Cult groups and military boot camps will use hard methods, which will induce violent mindset in the person (akin to what Christians would label as demons, or the ancients as malevolent spirits, though in truth they could just be different words describing the same thing e.g. 'super' and 'hyper', or 'big' and 'large'). It is similar to provoking someone into a fight by continually insulting them, they 'see red' and are 'taken over by the red mist'. They have been reduced to the almost chaotic state, and the violent provocation/stimulation from the other person has caused a violent mindset to take them over.
In a controlled environment, with a responsible teacher that the student trusts, this could be a useful method for inducing states of mind for the student, so that they can experience different states of mind, and, for want of a better word, grow, in maturity/spiritually/psychologically.
[T]he very institution of the so-called "Halls of Meditation" (Zendo), where those who strive to obtain a satori submit themselves to a regimen of life which is partially analogous to that of some Catholic religious orders, bespeaks the necessity of a preliminary preparation. This preparation may last for several years. The essence of Zen seems to consist in a maturation process, identical to the one in which one almost reaches a state of an acute existential instability. At that point, the slightest push is sufficient to produce a change of state, a spiritual breakthrough, the opening which leads to the "intuitive vision of one's nature". The Masters know the moment in which the mind of the disciple is mature and ready to open up; it is ten that they eventually give the final. Decisive push. This push may sometimes consist of a simple gesture, an exclamation, in something apparently irrelevant, or even illogical and absurd. This suffices to induce the collapse of the false notion of individuality. Thus, satori replaces this notion with the "normal state", and one assumes the "original face, which one had before creation."
[You still need to take some seed of belief or intention with you when you descend into madness/chaos, or have someone else outside ready to plant a seed/idea/intention in your mind, otherwise you will just be in chaos/madness with no desire to leave, no ability to leave, no intention to leave. You will turn mad, chaotic. A seed, intention, or question must be taken with you as you descend into the chaos, otherwise nothing good will come of it. It needn’t be anything that you are consciously aware of. It could just be a feeling, a hunch, a vague sense of something. i.e. something that you are unaware of but would like to understand. Or you could induce a feeling at the chaotic stage by listening to a particular piece of music. e.g. melody-heavy Schombert or beat-heavy Metallica.]