Practicing a short summary about yourself over and over and over would definitely help you be more fluent during an interview because you don’t really have to think on the spot and get flustered/cluttered. The issue is responding to adhoc questions you have not prepared for. That’s when you can stumble because the anxiety and adrenaline starts to surge. Take a beta blocker 1-2 hours before an interview to calm the physiological effects of anxiety and adrenaline. It’ll make you feel and appear calmer, and you’ll be able to gather your thoughts better.