Whilst the time may not be counted towards a JAA licence or rating, I doubt that the time is "non productive".
Would be a reasonable opportunity to refresh what the last lesson was all about before starting the actual training time, don't ya think?
On the way back it might be a decent opportunity for the instructor to demonstrate what he is going to teach next time - once they've done the touch and go.
Just shows really - what a load of bo****ks the rule is.