keep in mind that in any setting rural or metro that gps don't always contain all the "new" developments that just went up say a week ago. so if you run into that situation and your dependent on your GPS then you're going to be in a world or trouble. I used to work as a pizza drive in high school so i never have these problems. but like said, stress tests are designed to make you mess up and get flustered so that when your out in the field your better prepared for that type of situation and your supervisor knows that you can handle it.
The maps don't always have the new stuff either. Just keep in mind every so often you will get a run that isn't on your map. That is when it is time to problem solve!
Good luck to you. This will get easier.
J