@Saibisa ji,
I had practices reiki healing earlier and yes you are right a reiki healer requests reiki energies to flow for 24 hrs or till it get healed.
But this is a ritual being followed by the healers or we called it reiki energy will work for a quite long after a session, to be truthful it is just an asumption.
While when using VK it has own wisdom and it can give you that amount of energy in 30 minutes or less time ie; much much faster easy convenient and safe & secure.
Also with VK you don't need to first clean then charge then lock and finally cut as you are not the energy channel while sending energies with VK and hence no back effects.
Must read this article by @"Sharat Sir-VK Inventor" ji
https://www.litairian.com/reiki-side-effects-for-reiki-healers/