Venerable, at the beginning it was indeed as you say. There was running into trees while listening or not listening while walking. Quite chaotic and unproductive!
Yet gradually, with patient repetition and after much practice, the familiarity of the path as well as the familiarity with the sutta causes both to recede into the background. The foreground attends to the rise and fall of aggregates.
Over time it has actually become walking meditation. Indeed, I now count my breaths while walking listening to the suttas. In this way one knows that at that corner one hears …four immersions… at one hundred breaths while stepping around a car whose door is opening as the foot avoids a pebble. One simply attends without grasping. I understand this to be a meditation subject as a foundation of immersion is properly grasped, attended, borne in mind, and comprehended with wisdom. This is the heart of my practice and has lessened my suffering. It may or may not work for others.
However the critical point I wished to make was this. We should all recite the suttas together:
DN33:1.9.1: There are teachings … that have been rightly explained by the Buddha. You should all recite these in concert.
It is not in the reading or the listening. It is in the recitation.