Back when I used to live the commuting life, I was used to certain rituals of my morning journey into the city.
I took the same bus as a family member and would chat it up with him as we drove into Manhattan then branch off and take our respective subways. I'd see the same bus driver, same dude with oversized headphones I never made eye contact with. I'd pass the same coffee shop and wave to the same dude bringing bags of beans and cups and weird hipster-coffee-making paraphernalia. It was comforting.
It became such an ingrained part of my daily routine that any aberration was noticed immediately. If my relative wasn't on the bus, I'd look for him. If headphone guy was sick or when he suddenly changed his headphones out of nowhere, I noticed. When my bus driver was replaced with someone else, I didn't know how to feel about it but my initial reaction was, "NOOOOOOO!"