Staring at walls to improve focus and productivity

I came across a video by Simple Lucas describing a routine to improve focus and productivity. The routine was basically: Don&rsquo;t use any screens/entertainment when trying to focus on work. When you start to feel mentally drained, sit and stare at a wall for x minutes to recover focus. I&rsquo;ve been trying it, and it&rsquo;s a very effective (but hard) routine.