I posed this in the original question. However, my thoughts are that they should never be done, regardless of position in the pattern. Reason being, you are:
A: building bad habits that can show themselves at the wrong time. Sure, you might be able to switch it on and off whenever you want. But what if it accidentally rears its ugly head at the wrong time?
B: teaching students who are watching that it is ok to do turns like that near the ground. Students are impressionable, and pick up bad habits quicker than experienced jumpers, making it difficult to break them of it down the road.