I have typically thought of gaps as it relates to narrative literature, but if Gordon Wenham is right (see below), then I need to also pay attention to the gaps in poetic literature.
"Another technique that encourages the user of the psalms to adopt the psalmist's standpoint is the use of gaps. Gaps in narrative or poetry are points glided over by the author that the reader has to fill in from personal imagination to make sense of the passage. The terseness of poetry means that there are many gaps, which thereby force the reader to puzzle over the connection between one line and the next. The frequent mood swings in the psalms have long perplexed commentators and require every reciter of them at least to think of a connection between apparently contradictory statements. But more positively, the absence of many details within the psalms give them a general validity that allows their sentiments to be appropriated by readers in a variety of circumstances."
Gordon J. Wenham, Psalms as Torah: Reading Biblical Songs Ethically, Studies in Theological Interpretation (Grand Rapids: Baker, 2012),62.