Wanton? Actually, in Reingold Wagner calls for six harps, I believe -- most often in unison. Which, as Berlioz would tell you, is so you can hear them. For instance, in Berlioz's 'Roméo et Juliette', there are two harps in the Ball scene, but he recommends doubly or tripling each part so they can be heard properly over the rather loud orchestra.