…[W]hat you’re washing with has a much bigger statistical effect than how long you’re washing….
Another good example is the temperature you wash at. Namely, it doesn’t matter. Again, the issue is about the soap and about how you’re rubbing your hands around. That will work in cold water as well as warm. But the Food and Drug Administration’s food code for restaurant safety still expects hand-washing sinks to be able to deliver very hot water.