Rhythmic variation

Variation can actually enhance the strength of a pattern.¹ I think of how a drummer may do a different fill after each four-to-eight measures of a beat.

Variation in poetic meter can be an intentional choice, but it can also be quite natural on account of the words themselves.¹ Sometimes the most sensible line is one that doesn’t fall strictly in the meter. Gregory Alan Isakov does this well in his songwriting.