I remember a non hotel cleaning lady said she kept the used bars or remnants in a bucket for washing floors. That may have been when they still washed floors by hand on their knees.

If you leave tips, then you will see just how the soaps and small bottles seem to multiply every day!

A final hint. It is best to let the soap air dry, so that it doesn't 'melt' as fast with use. A ziplock bag would prevent that. High end face cleanser bars used to come in plastic soapcase type containers, and I saved them for use in my travel kit to hold bars too good to leave behind.
I put the slightly used bars into the plastic soap case and put it in the closet with my shave kit uncovered to 'air' or dry out.. Hate mushy soap in the shower. Then the maids can decide, if they want to leave more!
Usually pass on those tiny bars of soap in the lower cost hotels. Too small to handle and not worth the effort to save them except to take to a gym.