This is important because we should be working to live, not living to work.
Software engineering is challenging and I like solving problems. Sometimes when a problem is particularly interesting or stubborn, I find it difficult to tear myself away from that problem. In school, this manifests in my tardiness for things. Now that I have started my career, it manifests by forcing me to cut things out of my life.
One of my goals, and one thing that I think is a skill, is the ability to establish a boundary between work and life, and being able to consistently remove yourself away from your work when needed and when appropriate.
There is no “being finished work”, there will always be more work.
Its not a weakness to call it for the day, activities outside of work contribute to productivity by giving your brain a break and forcing you to be productive during designated hours and by making sure that you are not producing slop when you are too tired.