If you work on a product that has an existing user base that has an expectation that things will still work then you definitely still need to read the code. LLMs frequently break things or introduce subtle incompatibilities.
Maybe on projects with no users you can yolo things.
It's not about the number of users but the kind of software you develop.
In a mobile app, do you think it's more important to test that your drag gesture works as expected on the phone, or to understand every line of the implementation?