In our District, we have our kitchen staff leave their non-slip shoes at their location to prevent them having stuff on the bottom of their shoes from their homes (as we have staff that live on farms). Another reason we have them do this is as in the winter, the shoes become ice skates when snow gets packed in the grooves and especially on ice, so the shoes lose their grip. By having them keep their shoes at their location prevents random stuff coming in on their shoes and prevents slip and falls on the ice and snow.