We devote a lot of attention in music theory pedagogy to chords. But it isn’t enough to look at what the chords are; you have to consider when they are too. The placement of chord changes in musical time is called harmonic rhythm. The easiest way to understand this idea is to look at songs (or song sections) with only two chords. Philip Tagg calls these two-chord shuttles.
You can’t get much harmonic variety out of a two-chord shuttle by definition, but you can create interest by considering the timing of those two chords.