Mike there is a massive disparity between the glide performance of a grob and a Tobago, the grob is one of the best gliding primary trainers (have only flown one once but was impressed) the toboggan on the other hand (which I have instructed many hours in) glides like a crowbar. Perhaps this explains the different pattern, I'm not saying that it's right though all lighties should fly a similar pattern.
Great video GRIFFO it reflects a view I have expressed many times usually when I do I hear my least favourite line "thats how they do it in the airlines".