Use this when
A passage works slowly but becomes tense, messy, or unreliable when you try to bring it up to speed.
Practice Tool
Tempo Ladder
Build tempo gradually without guessing. Choose a passage, climb one rung at a time, and leave yourself a useful note about where the work became stable or shaky.
Listen for
The first tempo where accuracy, relaxation, tone, or timing starts to change.
Carry back
Save the highest solid tempo and the next target tempo, rather than simply writing that it needs more work.