One of the biggest mistakes actors make is not taking the time they need to prepare. While it is true that in an audition setting you will feel the pressure to be “there” on a dime, you’ve got to prepare or you will cut corners and just project your acting on your voice.
The more you spend solid time in rehearsal first particularizing your text and then fully preparing (emotionally) before you act it, the more you will be able to get to the depth of the material when you are forced to begin in a shortened time frame.
It is crazy that no one expects a violinist to walk out on stage and play without warming up her instrument but an actor rushes into talking her circumstance rather than finding a way into the depth of the circumstance.
If you don’t take the time to fully prepare and to be prepared at your rehearsals, the more you will short cut to your great disadvantage in performance and auditions.