When I get a tub of pipe tobacco, such as Carter Hall or Prince Albert, there is an insert that covers the tobacco. My thinking has been that the insert keeps the tobacco from drying out. Thinking this, after I finish filling a bowl, I put the insert back in, then close the top. The thinking being that it will help keep it moist. Am I correct or is this unnecessary because it doesn't really help, and the tubs don't really need it. For you who buy tubs, do you toss it or keep it in the tub?