How do you consider them? Did they give you anything or it's just was a waste of time?
Whenever I looking my repo, I see unfinished projects:
I wanted to build my next photographer portfolio in Node.js + Express, instead I went with Wordpress again. But in return, I learnt Node.js.
I wanted to create a website, which listing companies of my country with public data. This stage, I'm an unverified identity to get access for this official database from the government, so I built a web scraper in Go able to start the development and actually come up with a product. The project still hangs in this state. I never finished it, but now I know how to implement this in Go, how to work with files on the disk and use the standard library.
What are your letdowns, that hadn't payed you anything, but you learnt something new?