Quote - "I agree with your idea however of using secondary diffuse light sources in a scene, particularly if characters are involved because it delievers a greater amount of specular light.  Indirect lighting even with boosted sky domes produce no specular light so you will need additional diffuse light sources in order to generate specular highlights. "

True, but if the light balance is high enough (I use it around 80%) specular highlights are not a problem at all. There's no need to use secondary lights for this purpose, with this kind of light balance.

Besides, if secondary lights are used to iluminate the shadows, this can cause specular highlights in the shaded areas, and that's not very realistic, IMO.