One hopes the reader can figure it out. Stopping to let the character ponder the purpose -- even if in character -- would only slow down the story.
But lower than that are scenes that will have impact on the plot, and even vital impact, but don't have the obvious narrative drive. Adding more about motives, purposes, and intentions will sharpen the story and lend it forward motion.
And sometimes I still find, revising, that I put down what all the characters were doing but not why. Fortunately that's still clearer on revision. . . .
