See p14:
Standards Document 19 (A): Notes for the Guidance of Applicants taking the PPL Skill Test (Aeroplanes) | Publications | About the CAA
Fully developed stall...
Perhaps in some of the integrated schools the in house examiner will always tell the student to recover before the stall has fully developed? I doubt it. I've heard this idea of only going to incipient stage before but I'm not sure where its come from? Is it a non-UK thing?
However the instructor shouldn't be scaring their pupil. I'm guessing that the maneuver performed wasn't fully briefed? By recovering every time you should hopefully be able to build up the confidence.