Best neck training routine with a neck harness?

[Matheus]

I do 3x15 on each part with whatever weight gets me closest to soft failure at the end of each set.
Forward-backward
Rotation left + right
Lateral left + right

Currently I'm doing with an elastic band like in this video

 

[Matheus]

bump

 

[Matheus]

bump

 

[Matheus]

Still no answer. Is forward extension even necessary tbh?