"There is the case that 212man says of a small input or restriction - but the only case I could think of where I might use this is TO/Landing when you may be able to correct a small error without fully taking control"
NO!! That's very, very dangerous. The student might think it was a control restriction and overcontrol as a result. The ONLY safe method is the well-proven 'IHC/YHC' mantra.
Just print off this thread and pin it up on the Club noticeboard for the FI to read.