A "lane" requires people to simply walk behind someone else. Even if everyone is going in the same direction (or else the opposite one), staying in a lane requi

A "lane" requires people to simply walk behind someone else. Even if everyone is going in the same direction (or else the opposite one), staying in a lane requires patience. When some people are in great hurry compared to others, they start to look for ways of getting around their lane predecessor, disrupting the lanes. People not in a hurry will prefer to follow someone going the same way, because that person shields them from having to awkwardly dodge oncomers left or right. Either that person handles it directly, or else their own predecessor, etc.