That's the controversy. I do TDD at work and I don't for my contributions. I know both quite well. Most projects have little regressions and it is hard to quant

That's the controversy. I do TDD at work and I don't for my contributions. I know both quite well. Most projects have little regressions and it is hard to quantify upfront time you will hypothetically save later on, especially if all you do is contributing and moving to something else. There is some projects where TDD is down right vital, but most of the time, it is not.