Have yet to take the test myself, so take it with a grain of salt. However, I do follow this method. What a Yale lawyer told me was that he rotated the settings at which he took his PTs. So one day he'd be at the library, another at a busy coffee shop, maybe at home, or a quieter coffee shop. His rationale was that you want to prepare yourself for any distractions that may arise on test day, and the best way to do that is to not overfit your body's responses to one setting but to ensure that it is accustomed to a diverse set of situations.