Personally, I’ve never bothered to use a preservation box except as decoration, not enough slots. However, I’m sure that I read that you need to put ICE into it too for it to keep your food fresher.
As I say, don’t know for sure as I’ve never bothered to use one.
The improved preservation box now has 15 slots, which I feel finally makes it worth the trouble. Also, the preservation multiplier for foods that are already long lasting makes for a very stable food reserve. I’m also a fan of yog meat. Yum!!?