When we play we go through the item deck removing items not from the sets we intend to play with. (As we do for mythos, locations ect).
We do this with everything except the monsters, which are too much hassle to bother with in that way since they're not expansion marked.
What I'm wondering is if other people differ on this? Do some of you keep all the items in the game? I ask because it doesn't seem like it would have that much effect one way or the other. How do others feel about it?
