How often do you feel unit tests have helped you catch bugs?

I’ve had it help other people not break stuff I’ve written quite a few times, but almost never for catching bugs. TDD seems like it would add 30-40% dev time to an effort, and add cost to updates - I’m not a big fan of full test coverage. It just seems impractical from my experience.

As the line between reality and fantasy is increasingly becoming blurred, I want to be in a position to share the best of what I’ve been given. d/acc 

Yeah this is kinda where I’m at as well. I think a lot of people do it just to say they do it without considering the dev time tradeoff. I’m a big fan of MSW/some integration testing. Just curious what others thought. Thanks!