I have the new WB (brown and black fibers). One of my practice arrows (2315) has 5" feathers while the rest have 4" vanes.

After about 50 times through the WB the feathers are severely worn down: the odd feather is oriented up and it is the least worn (approximately 1/2" left) while the feather nearest the riser is worn down to about 3/8" and the feather farthest from the riser is down to about 1/4".

The vanes have little or no sign of wear.

It is interesting to note that the arrow with the severely worn feathers still flies well.