You may be nervous before your hearing, which can make you more likely to make a mistake. Your attorney will be very familiar with the procedure of hearings than you will be, and can tell you what to expect. This can help allay any fears you have before your hearing.
Your lawyer will no doubt want to practice asking you questions the judge might ask and helping you with your answers (testimony). Being well prepared to answer the judge’s questions can calm your nerves and make it less likely that you’ll say something that might inadvertently hurt your case.