Use of Cones While in RV Park or Campground

I always carry three cones for emergency situations while on the road. I use them behind my rig if I have to stop along the shoulder of the road for more than a few minutes. What's been your experience when set up in an RV Park or campground? Are they useful when parked? Have they saved your rig from damage from others who may not be as careful? Is three enough when in camp?