Certainly, it's necessary to place PARK BRAKE for any kind of parking. So, it should be good habit for you to do it after each parking even during the test, BUT if you don't do it, the examiner could give you at lease one "X" on form (you couldn't exceed 5 X to pass the test.)
However, maybe some examiners don't care about this. If you do it, they will give you a smile to encourage you. BUT, please DON"T forget to release it each time before starting to drive again.