Every audition disappointment I have ever heard about, mine included, traces back to the same lie: I had it in the practice room. You probably did have it. The problem is what the practice room counts as having it, because the room is grading you on a curve and the audition will not.
Three ways the room lies
First, the room lets you retry. You play the run, smudge it, play it again, nail it on the fourth pass, and move on satisfied. Your memory keeps the fourth take. The audition gets the first one, and your first-take percentage is a number most players have never once measured.
Second, the room always gets you warm. By the time you reach the hard excerpt you are twenty minutes into the session, hands loose, ear calibrated. The audition gets you after a car ride, a cold hallway, and a five-minute warmup in a room full of rivals.
Third, the room has no stakes, and stakes are the whole difference. Everything in your playing that depends on a calm nervous system, intonation, tempo, the quiet start of a phrase, is being tested in the easiest possible conditions and reported to you as your level.
Measure your first take, not your best take
The honest metric is simple: cold first takes, recorded, scored, no retries counted. If you want to know whether you are ready, that number is the only one that predicts the room.
Start every practice day by recording the audition program once, cold, before any warmup beyond open strings. One take. Whatever happens happens. Then practice normally. Over two weeks the cold-take recordings become a readiness curve that does not care how good attempt four was.
Listen back a day later, not immediately. Immediate listening is still inside the performance and hears intentions. Next-day listening hears what a panel hears, which is only the sound.
Make the room hostile on purpose
Once a week, stack the deck against yourself. No warmup. Stand instead of sit if your audition stands. Play the excerpts out of order on a shuffle. Invite someone to sit in the room, anyone, because one listener changes your nervous system more than ten empty chairs.
The point is not suffering. The point is that the version of you who shows up to the audition should have rehearsed being that person, not just rehearsed the notes.