In my head axial stiffness depends on that one angle (can be seen in my awesome drawing) which can only be changed by hub width or rim depth.
If you finish your sketch, you'll see that it is also changed slightly by the rotational offset between the two ends of the spoke, i.e. the number of crossings in a conventional build.
If you finish your sketch, you'll see that it is also changed slightly by the rotational offset between the two ends of the spoke, i.e. the number of crossings in a conventional build.