I wonder whether there's some hidden wisdom in the terminology. Agile "sprints" are (in the folk-wisdom) ideal for getting somewhere quickly precisely when you don't know where you want to finish. In this case a "quick sprint, rest, reorient, sprint again" metaphor seems appropriate.

On the other hand, long-running maintenance work with a stable goal over a year or more probably benefits much less from sprinting. I guess in this case we would need to know what "marathon" development would be :-)