Spirit Summoning and Dispatch could command wandering souls and wild ghosts because it exploited their incompleteness.
And when those Heaven and Earth Spirits underwent an Out-of-Body Experience, it was not a proper primordial spirit leaving the body either, but likewise a state of incompleteness.
In that state, those spirits could leave their original bodies and possess someone else, traveling to places tens of thousands of miles away from their true forms.
However, the possessed person needed to shake their head and body, actively creating a gap in the connection between body and soul—much like how Zhang Zhiwei had slapped Lu Jin hard enough to shake loose his upper dantian—so that it could link with the spirit's incomplete portion and complete the possession.
That incompleteness could likewise be exploited by Spirit Summoning and Dispatch. It did not matter if you had cultivated for a thousand years; if it wanted to seize you, it seized you.
But when facing a complete primordial spirit, or a living person whose body and soul were tightly fused as one, Spirit Summoning and Dispatch was ineffective. It could only rely on the spirits and ghosts it had captured to fight.
Under such circumstances, someone had actually cultivated themselves according to the method of ghost generals, deliberately creating that incompleteness within a living person... They were practically rushing to place themselves beneath someone else's blade.
All that could be said was that it was fortunate the Wang family had once belonged to the Divine Painting Lineage. If they had possessed any proper inheritance in Raising Yin Soldiers or manipulating Heaven and Earth Spirits, they would not have treated the Spirit Serving Technique as some precious treasure and used it on themselves.
As for whether those professionals had noticed...
Probably not many people in Daoism even knew that