And so, every time I go in a section of code to fix a bug or adjust a feature and I see his name in git blame... I spend another few hours to make sure that I'm not breaking some of the twisted framework code that he had and possibly fix it up a bit and adding a unit test for the functionality before I touch anything to assure myself that I know what it is doing.

An unproductive poor employee is bad... a productive bad employee is where the real problems are for years and years to follow.

You also need to factor in the odds of this whole process working.

There’s not a whole lot of empirical research that measures the correlation between the interview process and employee performance.

And of course, employee performance measurement is as dubiously effective as ever.

I've been a hiring manager before, and hiring good people is a huge time investment. The reality is that something like 99% of applicants aren't qualified, and the majority seemingly lack enough self-awareness to know it. The really good people also tend to be bad at marketing themselves. I don't think of interviews as a waste of time, though, even when it's a no-hire.