I code firmware for a heavily regulated medical device (where mistakes mean life and death), and I try to have AI write unit tests for me all the time, and I would say I spend about 3 days correcting and polishing what the AI gives me in 30 minutes. The first pass the AI gives me, likely saves a day of work, but you would have to be crazy to trust it blindly. I guarantee it is not giving you what you think it is or what you need. And writing the tests is when I usually find and fix issues in the code. If AI is writing tests that all pass without updating the code then it's likely falsely telling you the code is perfect when it isn't.