While I don’t want to try to belittle or negate your personal experience, but it flies in the face of a lot of industry best practice.
Also, you don’t actually give us any data. You say “This wasn’t helpful for my daily work”. Why not? What were you measuring to gauge the lack of effectiveness?
For a whole lot of people (myself included) code kata are a great way to hone your problem solving skills while at the same time increasing your fluency in your programming language of choice.