Years ago somebody told me that you should take your bar soap out of the box and let it harden/air dry, from the moment you bring it home from the store. I think the idea was that the soaps with moisturizer in them are partly "cleansing cream", which is a liquid, and liquids liquefy more quickly than solids. That is, they melt faster. So, if you air dry them for a good bit before you use them, they supposedly last longer. Theoretically. Nothing in my house lasts long....I have two teenager/young adults. Don't get me started on toilet paper, or milk.
mm