This really is an interesting training technique. It helps to train students to be constantly aware of the situation and look for details. It is a little prescribed in that the student knows there are problems to be found, but done enough times, and perhaps a little more on the sly- then new nurses should rapidly be paying attention to those details.
I see it as a modification of detail training in the military. You get drilled over and over as instructors look for anything wrong, thus forcing you to pay attention to detail all of the time. Though obviously this is less rigorous