In my experience, "line" is used because its intent is unmistakable. The last thing that an actor wants is to be prompted when he doesn't need it. Presumably, the prompter has his head in the book to be ready with an instant response and thus can't be watching for hand signals, significant looks, or raised eyebrows.
I don't know about this particular production, but there could be compelling reasons regarding sightlines, lighting, staging, or acoustics that would make it undesirable for the prompter to be in the wings.
In any case, I'm sure that this is a temporary expedient during early previews. |
