Is this not a form of meditation? I've never been able to keep a meditation habit, but my understanding is that meditation techniques often feature closing your eyes and focusing on breathing, body parts or some other irrelevant thing, it sounds like staring at a wall would serve the same purpose.
There's one where you are at rest and slowly shift the focus of your gaze from near to middle distance to far away, and back.
It's supposed to be a grounding exercise to bring your mind back to a state of rest and just observing.