Sprinters and marathon runners

Principals who visit classrooms to observe teachers are analogous to a well-rested sprinter running side-by-side with a runner who is in the middle of running a marathon.  There is a different level of energy, mental clarity, and strength between the two runners in that situation, just as there is between a principal and a classroom teacher.  I believe there would be a far greater probability of feedback from principals resulting in positive action by teachers if this analogy was openly acknowledged and embraced.