you don't wax to protect the life of your board. a thin layer of wax will not protect plastic.
you wax to go faster. if it didn't work then racers wouldn't waste so much time, tech, and money on it. race courses do not go thru flats.
on pow days in the PNW it for sure makes a difference and that's all i really care about.
on man-made snow i probably wouldn't bother with it but on pow or packed pow for sure.