I was recently involved in a tragic situation in which machine guarding failed not because the mechanical design was inadequate but because the human system around it fell victim to a well-known weakness. The case is currently embroiled in litigation, so I will refrain from naming names and will change a few minor details, but I think it holds a valuable message to keep top of mind.
We are creatures of habit and no matter what safety rules and policies we establish, employees can only be successful if safe behaviors become ingrained in their unconscious and automatic behavior.