Subframe Connector dilemma

I have question, when installing them,don't you check the straightness and square of the car 1st?I was helping in an installation about ten years ago.I remember stringing the axles to make sure the distance between the front and rear axles were the same.Run a string from the center of the rear wheel on one side to the front wheel on the same side of the car.Also we made sure the car was level.
Thanks