Vang Tension

Asking for advice on vang tension- I understand how to rig the vang but what I haven't seen explained anywhere in tuning guides is any reference as to how to calibrate how much to back off on vang tension for medium or light air. Is it a function of how hard you press down on the gooseneck before tying off or something else? Does anyone have any rules of thumb you use? I weigh about 215 and wondering if I should be using any vang tension at all in light air.
Thanks!