Once laying I DO also feed my shells back to the flock.
I don't rinse as being raised in California we have been taught to save water. I do set them on the counter and let them dry being sure they don't nest inside each other and let things start growing. Never had any smell or sick chickens...
Don't do it they don't need the added calcium as too much calcium *could* (doesn't mean will) cause kidney issues including gout and failure if fed long term to birds not in lay. It can also stunt growth and delay onset of production.
Once they are close to laying... absolutely. Meanwhile...