Why practising out loud changes the result
Most interview preparation happens silently, reading questions, thinking through answers, feeling ready. Then the interview starts and the answer comes out twice as long and half as clear as it was in your head.
That gap is mechanical rather than intellectual. Speaking a structured answer under mild pressure is a separate skill from knowing the material, and it is the one almost nobody rehearses. Candidates who practise aloud notice their own filler, their tendency to trail off, and the question they keep answering badly, none of which is visible from reading.
An AI interviewer is useful here specifically because it is low-stakes and repeatable. You can fail an answer four times at no cost, which is not true of a real interview and awkward to ask of a friend.