When mine wasn't talking, but would have whole conversations about space and trains and stuff using grunts and smiles they wanted us to reduce our speech to him to below the formally measured level of his comprehension. Basically they wanted us to withhold meaningful communication until he piped up. Exactly the kind of programme you describe. And there is some evidence that those programmes can cause longterm harm. I would guess by stressing the child by withholding meaningful conversation, and by eliminating opportunities to hear sentences.
The goal of therapy was to normalize his output without any regard for his special needs as a smart kid. His output was placed at 11 mos at the time. 6 months later, his output was placed at >4yrs (without intervention). If he'd heard no sentences from us would his first sentences have been, on average, 11 words long? I doubt it. But he heard us speaking to him at the level he understood, and so he kept learning, even while he was not producing speech.
But this is neither here nor there. I've sent my thing.
