I think you need to pick and choose your battles.

When I'm working on my own, I scrutinize every line of backend code and frequently send the LLM back for rework. Frontend code I keep an eye on just to make sure the LLM isn't getting stupid (which it occasionally does, even at the frontier), but mostly defer. The CSS I don't even look at.

This isn't too different from having employees. How much do I review other people's work? Depends on the employee, depends on how critical the work is.