I'm a developer with 5 YOE, and it doesn't really end. But honestly, unless you're definitely trying to get into the MANGA (formerly FAANG) world, I would focus much more on just building something to show to potential employers. I think that's more likely to make an impression on any arbitrary company, because almost every company I've ever interviewed with has not really cared about algorithmic problem solving skills. Most companies want to see your ability to produce software. Plus actually building something, imo, is much more emotionally satisfactory.