“Usefulness” is usually pigeon-holed as “doing stuff that makes us money so we can live a more comfortable life.”
But the best ideas come when we play and intentionally spend time doing stuff or building stuff that doesn’t serve some obvious purpose.
Don’t feel guilty taking the time to play a little. Explore ideas, play with words, feel every side of ideas and concepts in your mind. Don’t mindlessly cast stuff away because you can’t see how it helps you pay the bills.
Good moves are usually pretty obvious, but great moves take some thought and willingness to be creative and loose.
So don’t worry about everything being useful, because what you think is useful, is enough to get you by, but not enough to be truly great.