Watch the Patterns in Chord Changes online guitar lesson by Matthieu Brandt from Songwriting on Guitar

Repetition in chord sequences and the use of patterns are great ways to shape your songs and devide it in sections.
A songwriters task is to balance out the introduction of new elements and repeating parts. The most obvious element to a listener is the pattern or patterns with which the chords change. Repeating a chord pattern means there is space to listen to other elements of the song. Breaking a pattern will attract attention to the harmony.