Also keep in mind that the next cruise is boarding almost as soon as the last person on your cruise steps off. Your cabin steward only has 2 or 3 hours to clean all of his cabins and have them ready for the next group of anxious cruisers who are wanting into their cabins.
My guess is anything left in the cabin not of obvious value goes into the trash during the rush. I have heard of valuables being returned so that’s a credit to the character of the room stewards. Usable, but not valuable items. such as books probably get kept by the stewards.