Forum:How many terraformings in this deck?

If a decks main spell card is zombie world and uses it in a way that the structure deck does but also with soul absorbing bone tower so when they special summon they mill themselves and also with Il blud etc etc. How many of the chance should i make it I get zombie world? At the moment i use 2 terraformings and 2 zombie worlds but I'm thinking of taking out a terraforming and soon I will have 3 zombie worlds and might have no terraformings at all, just zombie worlds, any tips?