You really don't need to know the route. I'm sure in some way it makes you feel more prepared, but it doesn't necessarily make a difference.
There maybe parts of the route you are really concerned with that aren't even scored on the test.
If you miss a turn because you missed the directions and (didn't know the route) that's not an error. They can only mark when you do something improperly, so there are no demerit points for missing a turn. Also, knowing the route means you "know" what's coming up and you're anticipating it. If you're wrong, that may throw you off. Your decisions and your actions should just be based on where you're doing, not what you're thinking the examiner is going to say next.
