The jitters will always be a part of the MT life even after college. I always say jitters are good, if you didn’t have the jitters, then do you really want it?
Prescreens are rough, because no one likes to hear themselves sing, plus with the added pressure of the nature of MT you’ll always think you can do better.
The important thing to remember is that they chose this path because they are absolutely in love with it. Self doubt will never go away, but hopefully neither will the love they have for this.