I’m always amazed at the lengths people will go to in order to use every last bit of the soap slivers, when welding them to a new bar is so very easy. It takes about a second to do. I’m frugal with my money AND my time.
I’m really not that frugal, but I do this too. It is kinda silly since soap is so inexpensive, but I’ve done it forever. For me, I just like a big bar of soap to use and so I break out a new one long before the old one is a tiny sliver.