Mostly yes. It does deteriorate if left somewhere they stay damp, or sit in a puddle, but that's a function of the dish. So we always use something that isn't t

Mostly yes. It does deteriorate if left somewhere they stay damp, or sit in a puddle, but that's a function of the dish. So we always use something that isn't the simple puddle friendly indentation in ceramic often found in bathroom fittings. When they get small enough to be fiddly, I press the remnant of the old bar into the new one, so near zero waste.