Critically damped systems are the ideal systems it brings the object to stop in the least amount time, the damping is such that functions for position, velocity, and acceleration that we normally see in simple harmonic motion with a decay curve, the only remnants of the oscillatory motion in the very beginning of the curve (the up and the beginning of the decline).
The nice thing about critically damped systems is it the most efficient way to bring a motion to a stop. That a swing door as, the under damp system allows the door to swing back and forth over and over again until it final coming to a stop. With a critically damped the door closes as quick as possible, and if heated or cooled then the then there is as little temperuture change