Secret rituals are rarely seen these days, and even when they are, they often don't have any effect. Even if the person doesn't intend to, rituals tend to become very formal.
These types of rituals are originally more about fusion than about the ritual itself. Even if the person intends for it to be a ritual or for their own spiritual growth, the actual effect comes from the aspect of fusion. At that time, the basic principle of fusion is that there is a partner and mutual consent, and a ritual will not work without the consent of both parties.
In reality, this type of ritual is often performed so that a group of souls can share the same body to exchange experiences and knowledge. If the group of souls is different, even if the ritual is performed, it may be rejected by the group of souls, and even if it seems like the ritual was successful, nothing may change.
In a sense, the fusion of souls is like marriage, and it involves compatibility, and it is more about preference than about good or bad. Therefore, there is no need to worry if it doesn't work with a particular group; you can just do it with a group that works well.
This is a kind of fusion of a part of the soul, and a part of the light from the original soul, so-called group soul, descends and merges with the soul of the person participating in the secret ritual.
Then, it becomes like Piccolo from Dragon Ball, where two people become one, and the ratio is different, but in reality, the fusion of souls takes time, such as a year or more, and gradually changes, as if being reborn with a different personality.
In other words, what was originally performed with a group of souls that were originally connected has been misunderstood as something that anyone can do and become wonderful.
Also, there are groups that have misunderstood fusion as a separation from past mistakes.
Unlike the rituals performed in some schools, which involve severing ties with the past and being reborn, most schools only use the term "rebirth" to make it seem like that, but in the case of true rituals, soul fusion is involved, and you are truly reborn with a new personality. There seem to be schools that are imitating this and performing rituals.
Or, sometimes, they do something that seems to give something wonderful, but in reality, they are merging the karma of the disciples. This is a relatively irreversible thing, but there are many things in spirituality that are irreversible without knowing it, so this is just one example.
Also, this kind of experience happens to a person not necessarily through a ritual, but rather inevitably. If we call it a ritual, it can be associated with the ranking within the group, and even without substance, the ritual can precede the actual experience. However, for those who experience it, changes occur regardless of their position within the group. In reality, people who truly grow spiritually are often treated as troublesome within the group.
True soul fusion, or similar experiences, are often something that people who don't experience anything at all will never encounter, and many people who participate in the group's rituals will also remain unchanged. It is quite common for these experiences to be essentially only useful for creating a hierarchy within the group.
In that sense, it is inevitable that these kinds of rituals are kept secret, because no matter what you say, they will not be understood, and you will only be ridiculed by the group. Therefore, the attitude of not talking about it to anyone other than true comrades has continued for thousands of years.
Recently, the trend has started to change, and spiritual knowledge has begun to spread, but basically, I don't think things have changed that much.
It's like, "It's pointless to say it," because ultimately, it depends on the soul group and the origin, which would discourage people who want to practice spiritually.
However, even so, if you continue to practice for generations, you will grow, and it is never a waste of time.