Just to reinforce what @P1xt said, it’s good to go back to older projects once you have more expertise under your belt.
I’d add to this my own experience:
While I was working on my Nightlife Coordination app in the backend projects, I decided I wanted to use Sass and Flexbox. Rather than try to learn those two new things while also building a new app from scratch, I decided to go back and use Sass and flexbox to revamp my Weather app. That way I didn’t have to solve the ‘business-logic’ problems of the new app while also learning the styling technology I wanted to use. Learning the style stuff in the safety of a previously completed app meant I could reduce my cognitive load and solely focus on the one thing I was interested in learning. When I finished that and went back to the Nightlife app, implementing flexbox and Sass was much easier, and I could concentrate on getting that app working instead.