In my current role I've done about 30 whiteboard interviews in the last 2.5 years, and I come down on the side that they are about as predictive as throwing darts.

The most successful candidates I've helped hire in my career were the ones where we had an informal process where we just talked about things and I went with my gut. They say that's not objective or measurable, full of bias, etc.

I toss my hands up in frustration.