Don't speak to them or help them at all?

Suppose they get stuck on the first step in a multistep procedure. Do you just let them keep flailing on that step for however long they are available, so all that you learn from that entire session is that the first step needs rewriting? Or do you end the test and let them go, again learning nothing beyond that the documentation for the first step sucks?

Wouldn't it be better at that point to help them on to the next step and then continue on having them test the rest of the steps?