A scene is planned in advanced, than the animator would create a rough sketches that portrays the character's progress in his action; although the rough sketches will not be used in the real animation production, they serve as a guide for the character's width, height, position, attitude, relationship with the backgrounds and foregrounds.
They offer much control over the scene even though some animators feel that over-control leads to a still character that is not spontaneous and live. They say that 'An animator should discover the outcome just as his audience'.
Acting requires different approach than a matched background that is not moving and the character should do something with it. Acting requires the animator to plan his character's actions. For example, if a character seems unhappy, it would lower its shoulders, turn around, lower its head and walk slowly with a sad face. This must be done with a Pose to Pose method because each frame must be drawn carefully for maximum clarity, appeal to the audience.