Every aircraft has an effective stall warning. It's in your hand. When it's hauled back to your stomach your pretty close to a stall. Learn where the stall stick position is and you don't need any "clacking" as a
If you believe that garbage, then the standard of aeronautical knowledge has declined badly in some quarters.
Splitting hairs a bit, but I was under the impression that the pieces of kit were called slats, and the the flow of air was directed through the slots formed, thus delaying the onset of turbulent flow over the upper wing surface.