Noctave
The piece
Two hands climbing together in parallel scales, a tenth apart, then broken chords coming back down in small hops: this C major study, marked Allegro, puts both hands on an equal footing from the first bar. The second part sets them talking, the right hand tossing out a broken chord that the left answers lower down. Later the right hand repeats an E while a neighbouring note climbs above it step by step.
The parallel scales are the real subject. The thumbs do not cross at the same moment in both hands, and that is exactly where the sixteenths slip out of line. Practise each hand alone and note where its thumb passes, then put them together very slowly, checking that both land on the eighth note at once. In the broken chords, each pair is slurred then detached: drop the hand onto the first note and lift it on the second. The left hand, at up to four notes per second, needs the same clarity. Wait mode helps line up the two thumbs before you play in time.