My company requires us to do them once an hour. Even though most don't do them at all. It's to make the store look cleaner and have a smaller percentage of customers tripping on debris.
Because its policy. If someone slips and falls, management looks back at the cameras and sees who was doing sweeps at that time. If its proven that a sweep was done, then you are in the clear and the company is free from a possible lawsuit. IF the sweep was done CORRECTLY.
If no sweep was done and logged in, then the potential lawsuit can and will go through and the one who was on sweeps at that time can and will possibly be discharged depending if management likes you or if it's your first offense.. we've had scammers TRY and claim that they slipped and fell but when we looked at the camera it was proven we did the sweep so we were in the clear much yo their chagrin.