One of my first projects as a junior front-end developer was a fast food delivery app.
When I showed my father the app I built, he was excited for me and he wanted to try it. Unfortunately, he uses an old Dell 620. He really likes the computer's form factor and it works fine for him. Why would he upgrade?
Then I saw him trying to use the app. He was confused, and he didn't know how to navigate through the app. The performance was also horrible. I blocked the DOM multiple times, and overworked his CPU while parsing the entire food catalog twice. That's the result of inexperience.
Now when implementing a feature I like to put a face on the average customer, the face of my father. It puts things into perspective and throws out of the window every half-ass implementation I would normally feel alright with.