Wilderblade mob head drops.

This is my personal opinion but I would like to see the chances of getting a mob to drop its head using a wilderblade move favourable for the player. I've spent many hours trying to get all the heads in the September list but am not even close to getting them all. I have limited to time to play on the server each day and it would be nice to find a good balance between hunting for mob heads and building my base.

Thanks

PJ
 

This is my guess so I'm not sure if it's true or not: I'm not sure if the system was designed so that a single person would be able to get all mob heads within the limited time window. Making the drops rare allows people to create a market for them. Similar to a trading card game, you can only get so many (due to the rarity of certain mobs) and are encouraged to trade with others for the ones you want. 

Now the question becomes, if this is true, are the mob heads eventually cycled in and out so players can get a chance at specific heads later on? A Mod would have to verify this information.