A very slow tempo may require a different chord for every melody note. A moderate tempo may require a different chord every beat or two, whereas, a fast tempo may require only one chord per measure. These are generalizations, of course. An appropriate tempo can be determined only by careful study of the melody and applying one s own aesthetic judgment. Harmonic Rhythm .
Harmonic rhythm is the frequency of harmonic change in a composition.
When a change of chord appears on a strong beat of the measure, it may extend into following beats. An exception occurs when a new phrase or motive begins on a strong beat, in which case the harmony of the previous weak beat may be repeated. Typically, there is no harmony at all. But, if the upbeat to a phrase is harmonized, the harmony may be repeated or changed on the strong beat that follows. Rhythmic syncopation is generally avoided in harmonic rhythm.