Repetition is not a character test
Accept that useful practice can still be tedious.
One clean attempt shows that you can play the part. Repeating it cleanly makes that version easier to play again without thinking about every note.
Why one good repetition is not enough
For a drummer it might be a sticking or foot pattern. For another musician it could be a fingering, chord change, bow stroke or articulation. Whatever the instrument, clean repetitions make the way you want to play it easier to find again.
Unfortunately, understanding a part often comes well before being able to play it reliably. The remaining work is not intellectually difficult. You know what to do. You simply need more correct repetitions than your brain finds interesting.
