Coding competitions are a good way to test and improve your skills. Some of the skills you might already have just by the nature of the engineering job itself - you have to set up your development environments, trouble-shoot connectivity issues, and solve problems when they occur. I don’t need to tell you that it’s better to learn these skills in a controlled environment, and perhaps not while watching your production systems fail. And in case that does happen - you don’t want to be the one who’s just looking at whatever metrics you have and pray for some kind of miracle. But, putting a time limit on a competition - it keeps some pressure on you, just like the real thing.