I didn't call people who stay just one or two days a leech. To be a leech you have to empty the *whole* FC chest during your short visit. Probably to make gil because I can't imagine you have a personal need for the variety of items to be found in a full chest.

That having said, of course I simply could generally restrict access to new members before promoting them to a rank giving them more access. But I don't like that since it blocks new people from reasonable take outs (as in materia melting for their gear or food for crafting/gathering buffs.

A FC member history would simply allow me to better assess the risks of a potential leech. A person who jumped FCs 3 or 4 times the past week would just start with lowest privileges while someone who stayed at least a few days would start with more access.