The last place was the Porsche shop I worked at. It was very annoying, and the car went in and out of the shop so many times I don't care to remember. This was on a new car, just purchased. It escalated to the point of invoking the local lemon laws on the car, and contacting the manufacturer. The manufacturer told me that this is something that they are now considering requireing in all their authorized shops due to the way the cars are made.
Tires can also be out of round and cause an inability to balance correctly.
I also agree that changing tires too often is a real bother. I have always lived with the little 45-60 MPH shimmy in my 2002.