I noticed that ascending in the RH is more difficult, and descending in the LH is more difficult.
I noticed that ascending in the RH is more difficult, and descending in the LH is more difficult. is this what you are talking about?If so I think it is because the natural way to use the thumb is not the most obvious way. If you want fast and pearly scales you can't cross the thumb under but rather the hand moves sideways and the thumb plays then. Not perfectly sideways, but in an elegent arch.Walter Ramsey