If you are going to use that dealership going forward, make an appointment with the service manager and sit down with him.
Let him know that you would prefer if they have to take the car out to check anything that they take you with. Then remind the service writers each time you visit.

I'm not so sure that checking the GPS function on a replacement radio/Nav is 100% BS. Perhaps the duration was excessive but I wasn't there.

Most of their customers could likely care less as long as the car is returned working but since you do, calmly explain what you expect to the man in charge and build a relationship with him. It could mean the difference between some free TSB or out of warranty work and paying for it in the future.