You can add all the things to the challenge to make it better: business requirements, art direction, target users, flows, etc. It could be a lot of work to do this well daily, but scoping is also a good skill to learn. It's also make a better designer by learning new knowledge domains. So... it depends, on how you do the challenge. At the very least, even the simplest UI and just for the sake of styling, if you keep making it for a 100 days, you'll definitely learn a few things.
You can add all the things to the challenge to make it better: business requirements, art direction, target users, flows, etc. It could be a lot of work to do this well daily, but scoping is also a good skill to learn. It's also make a better designer by learning new knowledge domains. So... it depends, on how you do the challenge. At the very least, even the simplest UI and just for the sake of styling, if you keep making it for a 100 days, you'll definitely learn a few things.