I would suggest the actor, in an attempt to discover variety in a scene (variety is the spice of life, after all...and acting), rehearse any scene from a variety of emotional tacks: once angrily throughout the whole scene, sadly once, happilyy once. Benefits accrue: the actor will soon discover the host of emotional possibilities inherent in the scene…and in the actor/character herself. Scenes (and dialogue and movements within them) are extremely malleable, almost infinitely elastic. Personally, I have said the same words and sentences to someone in a conflict at one time with extreme rage, while at a later time had the same conversations…with the same person with the exact same dialogue….while tickling the other person and laughing.
By approaching rehearsal of any scene in that wide-ranging manner, actors can begin to pick and choose what attitudes and emotions work best on what lines and sections of a scene; and begin to emotionally sculpt their scenes accordingly...and always with variety in mind.