The Goetic demons are said to command many legions or minions. Are you supposed to feel and see these legions/associates when you bring the demon down also?
Sometimes, depending on the task at hand. If you are just needing some grunt work done, the horde will manifest, because that’s what you request. Should you just need a chat, then you only need the full demon. The horde are like programs. Not as intelligent, but relentless. My experience. Opinions may vary.
EA’s Works of Darkness does a great job of demonstrating both scenarios.