Many of the pentacle of the GKoS (maybe most) don't have spirit names in thier design. Most have angel's name, but rarely list associated spirits.
As I read that grimiors operations of conjuring and binding, its specific that a spirit is conjured, and possibly threatened and punished. Obviously that wouldn't be any
associated angel.
How do you know which spirit should be called for a particular pentacle? I don't read anything that stands out in the GKoS ?

And for pentacle with no direct angel or spirit . . . . what name does one use?