I don't see it mentioned often, and I expected to see it here but didn't: Writing harder code makes you better at writing easier code. It's easy to continue a

I don't see it mentioned often, and I expected to see it here but didn't: Writing harder code makes you better at writing easier code. It's easy to continue at your same level and just go forever, not improving. If you challenge yourself, even on a project that doesn't matter, your code at lower levels will improve automatically. The lessons you learn from coding harder things will translate into better coding all around.