The loop technique is a great way of saving time when creating an animation. It allows the animators to reuse already made material, and not have to create new material. The most famous loops in animation are used in the classic Scooby Doo series.
In the scene above, we see a usual scene of Scooby and Shaggy running away from the villain. There is a loop here with the background. It is constantly repeated and gives us a sense that the characters are running a long distance.
Another classic that uses the loop technique is Road Runner. The background, like Scooby Doo is repeated to give us a sense that they are running for a very long time and over a far distance.