I have a question regarding this instruction in Schmitt (this book suffers from trying to be too concise sometimes, I feel, at the expense of clarity!) Practise with the C major fingering. Does this mean, for example, practise D major with LH 5321 3212 3123 AND 5421 4212 4124? And even to do 5421 etc on keys such as E flat where it feels very awkward?
This question follows several lately asking about piano fingering.
The numbering in any tutor book is suggested, not obligatory. And the suggestions here are questionable - hence your question..!
Use any suggested fingerings as guides, but if they aren't working particularly well - or not at alll - then come up with your own solutions. Even in exam situations, the scale and arpeggio section is marked purely on execution musically and tempo wise. No bias is applied to the fingering thereof. In fact, often the examiner won't look at or be able to see the candidates fingerings.
A simple ti for playing smooth arpeggios - keep the hand moving sideways constantly, so the fingers used are over their notes. That rather than swivelling from the wrist to reach the next note/s.