How "hand on" should an instructor be?"
The posting I am replying to reminds me of a relatively recent incident that involved me in renewing my Altiport rating for a well known French alpine ski resort. This was my 10th year of annual renewal. Let me say that I am a professional pilot with extensive experience on type and on many other types. I say this to emphasise that I am not an ab-initio student.
This particular check instructor had a habit of 'nudging' the controls either forward, or back, and also in roll mode without any prior warning, or clear intention. There was no standaer convention. Whilst mildly acceptable at a safe altitude, it became a serious matter on short finals where there was a real danger of a "who has control" question. Worse still, there was an even greater danger of an unintentional and potentially lethal wrestling match ensuing between me and the instructor taking place very, very close to the ground.
I terminated the flight myself by positively handing over to the instrctor accompanied by a very emphatic "you have control", and resolved never to fly with that individual ever again. As far as I know he never took the hint, as I found out some time later that I was not alone in my experiences
He was killed alng with his student in 'unexplained conditions', a few weeks later.