The concept of this “drill” is obviously to train the kids to act in a certain way, when faced with this kind of situation, which would result in success. But in the case of a suicidal gunman success can only be defined as death for the gunman with no casualties.
If it became absolutely necessary, kids could be trained in such a way that they would at least have a better chance than with no training, especially if the gunman is not suicidal. But the training exercises would have to be very different from this one in Murfreesboro and the trainers would have to be competent. There are potentially severe psychological side effects. At this point any such training is still a bad idea. Cost far outweighs benefits. Arming some of the teachers would be much more logical.
I read somewhere that some terrorist experts state that the schools need to teach the teachers and the students that they should flee in a zig zag pattern away from the school if presented with the opportunity to escape.