Many students have problems that they are just not aware of. Thus a habit breaker is required.
I have used the technique of getting the student to say aloud the scan technique.
Attitude = checking the horizon is in the required place in the windscreen, ie pitch and roll
Lookout = checking for traffic
Performance = IAS and or Alt and trim feel.
Check to see if the student has a death grip on the control column as this will reduce the feel of the trimmed condition.
I recently flew with a 15 yr PPL veteran who couldn't fly a 180 deg turn without losing significant height. After completing the attitude flying sequence a few times with the instruments covered, the performance improved greatly. The student said that attitude flying was a new thing to them.
Difficult to believe but I am sure the student thought this to be the case.
This was the worst case I had seen of non-attitude flying, but it was easily fixed once the student is made aware of how they can judge the aircraft's performance by looking out the window. They can't keep a car in the centre of the road land by looking at the speedo, yet they think they can do it first up in the aircraft.