Why are you giving instruction during a Stage Check? The purpose of a Stage Check is to determine if a student meets the standards for that phase of his/her training. If the student could not fly a stabilized approach I guess I could understand making some suggestions but shouldn't the subject of new techniques be taken up the the student's primary instructor? When students are not performing well on a Stage Check I ask them what went wrong. Most of the time they know and after they explain it to me they are able to correct it on a second try. If they don't know what they are doing wrong it's time to end the flight and go have a talk with their instructor. Take a look at the lesson plan for the Stage Checks in your syllabus, I bet you will not find the word "Introduce".