Observing Lessons - I've Never Learned More as a Teacher

I learn far more from those visits than anybody does for me, I absolutely love it. But my fear is, and I'm interested how they do this at Tatcharage, that it's your heads of department who watch lessons. And maybe it's your ECTs who sometimes get to watch lessons as part of like an ECT program or whatever. Because we know watching other teachers is such a beneficial thing,. so how does it work at TTA? Do you get round that problem at all? We don't have it correct. You say to them, go observe someone, in what image do you have in your time? So it's a very tough nut to crack,