No Instructor is going to fly a single 'demo' circuit and let that count for revalidation and why would they, I know I don't? The pilot has sought training and why would a qualified pilot need an Instructor to manipulate the controls for them?
Bose,
Who said anything about revalidation?
We are talking about meeting the JAR-FCL requirements for carrying passengers.
When you gain soem experience as an instructor you will find that there are plenty of times when "a qualified pilot need an Instructor to manipulate the controls for them".
For example, many pilots forget to select carb heat before reducing power. Do you reach down and select it? If not then I bet you tell them to select it.
Of course, the way things work out often the pilot may only need to complete 1 take-off and landing on order to have the required 3 in the past 90 days.
Regards,
DFC