There are too many scales in ABRSM piano exams: far more than for other instruments - and I have sat across the table from the chief examiner and told her so. Why are there just scales and arpeggios and not technical exercises, as for other instruments?
Anyway, I can pretty much predict what students will find harder at the higher grades:
- Diminished and Dominant Sevenths
- Minor scales starting on black notes (especially melodic minors)
- Scales in thirds and sixths - especially the black note minors again
Thank goodness that contrary motion scales are dropped in Grade 8 - don't get me wrong: I practise contrary motion scales - they wake me up at the start of practice sessions - they separate the swans from the geese, as it were.