The objective of most published tuning rules is "tight" or fast control, subject to avhieving acceptable robustness. This gives a maximum limit on the controller gain. In industrial practice, however, the objective is often "smooth" or slow control, subject to achieving acceptable performance in terms of disturbance rejection. This paper provides the corresponding minimum limit on the controller gain. In terms of appropriately scaled variables, the minimum controller gain is approximately 1, which justifies default settings commonly used in industry.