Routines provide us with comfort, control, and can reduce stress levels. They help us relax and can reduce anxiety. Think about how it feels for you, to be thrown out of your normal routine. It can be stressful for some of us! Now think about this happening when you are in a new and strange place. That's uncomfortable, or even scary.
It can be the same with our dogs. Routines can help provide comfort, especially in new environments. It's important to note that like everything with our dogs, this is an individual thing - routines can be less important for some dogs, and have more of an impact with other dogs.