Review precision first
Look at timing before increasing tempo. Speed without clean placement usually compounds instability.
Hanon becomes more useful when the run can be reviewed instead of remembered. A MIDI keyboard adds timing, pitch, and control data to each repetition so practice can be adjusted with evidence rather than guesswork.
Keep the session narrow enough that any change in timing or evenness is visible.
Confirm the iPhone or iPad sees the Bluetooth or wired MIDI device and the app is receiving notes.
Use a small number of runs, review the result, then change tempo or articulation on purpose.
Look at timing before increasing tempo. Speed without clean placement usually compounds instability.
Increase only when the previous target is stable enough to feel repeatable, not merely achievable once.
After each run, name one adjustment for the next repetition: finger evenness, release timing, or hand balance.