year8+12+bar+blues

In a blues song this 12-bar cycle gets repeated over and over through the course of the tune. A blues song might play through it 20 times. It will depend on the specific song.
== The blues can be played in any key. In whatever key you are in, 12-bar blues uses the same basic sequence of I, IV, and V chords. It is most easily thought of as three 4-bar sections – the first 4, the middle 4, and the last 4 bars. ==