EDDNR - how can I thank you enough!
You have researched and come up with the answer to something that has been bothering me for some time.
When I came back, a couple of years ago, with a shiny new PPL from foreign parts, I was checked out by a rather nervous instructor. On downwind, after my checks, he used these precise words: "Don't be so relaxed"!!
I didn't like to ask why not, and it had been bothering me ever since. NOW I KNOW! Gosh, if we had both been relaxed, who knows what might have happened. I heard he gave up instructing soon afterwards - maybe he became too relaxed and the risks just became too much.
Now that I KNOW, I will always make sure I have at least one nervous passenger on board (I only fly small planes so only need a little lift).
Knowledge is a wonderful thing.