One-part paints are soft and lack the robust composition of activated urethane coatings, which can generally tolerate buffing better. If not done very very carefully, it is very easy to burn through or soften 1-component paints, which will result in a smudged look. When buffed, a shinier surface can be achieved but due to the softness, too much of the coating film is buffed away, leaving much lower UV protection, and the finish can haze or fade much faster. Buffing old, faded paint may be a last resort attempt to bring out a shinier surface or truer color, but it should not be expected to yield good, or lasting results.
For the best longevity and shine of any 1-part paints, it is recommended to properly reapply a coat every few years, or as the paint begins to fade (whichever comes first).