AeroPod, PowerPod and Newton

i use my ibike from TT bike to standard roadie to mtb. how important is the little green plastic vein in the wind port? do i need to put it in?

In our most recent testing we have determined that the wind vane is optional for most ride conditions.

out of curiosity when is the vane most important and what is the effect in the case where it makes a difference? For instance i was thinking about this yesterday while riding in a really strong cross wind (50 km/h with gusts coming from a yaw angle nearly 15-45 deg).