Those who possess supernormal capabilities or who are sensitive may know or feel it in sleep or some other time when they suddenly feel a hot current penetrating all through their bodies coming down from the head. The purpose of filling energy this way is not to add high cultivation energy to you, because cultivation energy can only be acquired through personal cultivation. Filling energy into the top of the head is a reinforcing method to purify and to further clean up your bodies. There are many times where filling energy into the top of the head will occur on every level to clean up your bodies. We do not practise the formality of filling energy into the top of the head because cultivation is one's own business, while the evolution of cultivation energy is done by one's master.
Some people still practise something like formally acknowledging somebody as their master.
Speaking of it, I would like to mention, by the way, that many people want to take me as their master. This historical time of ours is different from the feudal society of China. We do not practise such a formality. I would say that is ridiculous. Genuine cultivation depends upon oneself.