Javaでのスレッド優先度の重要性？

public class ThreadPriorityTest extends Thread {
   public static void main(String[]args) {
      ThreadPriorityTest thread1 = new ThreadPriorityTest();
      ThreadPriorityTest thread2 = new ThreadPriorityTest();
      ThreadPriorityTest thread3 = new ThreadPriorityTest();
      System.out.println("Default thread priority of thread1: " + thread1.getPriority());
      System.out.println("Default thread priority of thread2: " + thread2.getPriority());
      System.out.println("Default thread priority of thread3: " + thread3.getPriority());
      thread1.setPriority(8);
      thread2.setPriority(3);
      thread3.setPriority(6);
      System.out.println("New thread priority of thread1: " + thread1.getPriority());
      System.out.println("New thread priority of thread2: " + thread2.getPriority());
      System.out.println("New thread priority of thread3: " + thread3.getPriority());
   }
}

Default thread priority of thread1: 5
Default thread priority of thread2: 5
Default thread priority of thread3: 5
New thread priority of thread1: 8
New thread priority of thread2: 3
New thread priority of thread3: 6