None whatsoever.
Just work on repertory s/he loves and that is either easy or challenging, but never difficult or impossible.
For the full story have a look here:
https://www.pianoforum.net/smf/index.php/topic,8981.msg91081.html#msg91081(repertory x purely technical exercises to acquire technique)
https://www.pianostreet.com/smf/index.php/topic,15879.0.html(play only what you love – difficult x challenging pieces)
https://pianoforum.net/smf/index.php/topic,2429.msg21061.html#msg21061(Technical studies x pieces – the genesis of Studies and how Czerny derived his exercises from Beethoven sonatas - why scales are useless and at the same time essential – Chopin x Kalkbrenner story – Unorthodox fingering for scales).
https://pianoforum.net/smf/index.php/topic,3625.msg32673.html#msg32673(PPI – comparison with body building – brief mention of movement and intellectual centre – comparison with babies walking and coma patients- muscle tension and nerve inhibition – how to investigate and test practice ideas – How to teach by using progressively difficult repertory)
https://pianoforum.net/smf/index.php/topic,2998.msg26268.html#msg26268(Scales HT, why? – why and when to practise scales HS and HT – Pragmatical x logical way of teaching – analogy with aikido – list of piano techniques – DVORAK – realistic x sports martial arts – technique and how to acquire it by solving technical problems – Hanon and why it should be avoided - Lemmings)
https://www.pianostreet.com/smf/index.php/topic,2619.msg104249.html#msg104249(Scale fingering must be modified according to the piece – Godard op. 149 no.5 – yet another example of the folly of technical exercises)
https://www.pianostreet.com/smf/index.php/topic,2619.msg104249.html#msg104249(Scale fingering must be modified according to the piece – Godard op. 149 no.5 – yet another example of the folly of technical exercises)
https://pianoforum.net/smf/index.php/topic,4385.msg41226.html#msg41226(technique is personal and relative to the piece – Fosberry flop – the best books on technique)
https://pianoforum.net/smf/index.php/topic,4734.msg44770.html#msg44770(how to acquire virtuoso technique – aiming at 100 pieces in five years)
https://pianoforum.net/smf/index.php/topic,5352.msg50998.html#msg50998(Exercises x repertory – why technique cannot be isolated from music – analogy with warmup in the martial arts – dynamic flexibility and co-ordination – how to do high kicks without warming up)
https://pianoforum.net/smf/index.php/topic,5375.msg51272.html#msg51272(Defending technicalexercises – two different philosophies regarding exercises – chopstick analogy)
https://www.pianostreet.com/smf/index.php/topic,7341.msg114168.html#msg114168(repeated note-groups for difficult passages – correct technique is never uncomfortable – rotation as the solution to 5th finger weakness – criticism to misguided technical exercises – trusting the unconscious)
https://www.pianostreet.com/smf/index.php?topic=13583.msg147163#msg147163(Why Hanon is a waste of time – or not - summary of arguments and many relevant links)
Tip of the iceberg…
If you are still interested in submitting your poor charge to technical exercises, take your pick here. With few exceptions (e.g. Heller, J. S. Bach) they are all equally useless.
https://www.pianostreet.com/smf/index.php/topic,11179.msg117263.html#msg117263(extensive list of technical exercises and etudes)
Best wishes,
Bernhard
Topic: Exercises