Cycles

This principle is basic and very useful. Cycles are used to repeat a sequence of animation over and over again, they are very useful for walks where the main action is being repeated. Alternatively they are useful for things that are less important within the frame, for example a camp fire crackling away in the background. It isn't important enough in the story for viewers to be distracted by the movement and therefore a cycle is appropriate. On the other hand, if the fire was a a raging fire that was a threat to the character and therefore key to the story line, it would have to be animated as a full sequence such as in Bambi.

cycle of fire

bambi fire sequence

(the fire sequence begins at 2mins40)