Well, depends. My thousand-line pet project does not need any tests, it needs to be feature complete and never touched again.

Bigger projects are usually ones where multiple people are contributing and having code that practically nobody wrote there is a huge problem on it's own in my opinion, even if it passes a number of tests. Good tests themselves are usually harder to write than the code they are testing, I am not sure if delegating the actual fun part of development to an LLM and doing "chores" manually is a good idea.