From what I've seen, right now it seems as though the night-night method is only a theoretical way of ctb-ing based on the possibility of death from chokeholds (only in this case, having that pressure sustained).
If you look through the threads about it further, you will see a lot of SS posters struggling to it pull off despite many attempts/different materials/positions.
So far, the only case where I've heard of someone using this method and successfuly ctb-ing is a video clip (its usually on gore sites) of someone using the ratchet and cornhole bags. That said, I have my doubts that it was done correctly, as it seems to have been more of a struggle rather than passing out almost immediately.
So, in short, it sounds easier said than done to use the night-night method.
In contrast, something like SN or Halatal, though harder to source, has shown to be much more peaceful, fast-acting, and easier with SI (drinking a liquid instead of self-strangulation). With the right dosage, purity, and meds to help keep it down, chances of dying are higher.
Unless people work out/refine the night-night method to be more reliable, I see SN or N being the go-to for now