This question was sent by Jur. And he writes:
My biggest challenge is still to be patient and not rush ahead in a piece before I have mastered it bit by bit. I know this is a very bad habit and this is the reason why I never can play without making mistakes. I am trying to find the discipline!
Practising just one piece does get a bit boring so in addition to BWV 639 I have now also started working on BWV 731. I have practised this in the past but with different fingering, I am now relearning it with yours.
Best regards,
Jur