It is unreasonable to buy a better piano each year to track the increasing technical demands of higher grade pieces, but it is a wise move to upgrade the piano as soon as the player has exhausted its capabilities. A starter piano will get a young player going but eventually, for a keen and talented student, it will be a source of frustration and discouragement.
The piano used for exams should also be a good quality instrument - and in good order. There can be nothing more intimidating for a young student to be introduced to the exam piano only to find that it is unresponsive, heavy to play or in need of tuning. A young student encountering an 'unfriendly' piano, has to work very hard to keep their 'cool', - this is an unwelcome pressure to add to the concerns of taking the exam anyway.
One would not wish to make piano exams easier, but a better piano goes a very long way towards giving the student a fair chance to do credit to himself. It is certain that some pianos used for piano exams simply unsatisfactory. I am not sure if exam boards have any effective 'quality' assessment of the pianos used for their exams, but it would be beneficial to everyone that some quality control system were set up.
© Steve Burden