They were unfit to complete the tasks. But again was not their fault, I think was the hiring that failed.

One concrete example was the fact that our pipelines was quite straightforward for data engineers: packaged Ruby and Python CLIs that runs commands. The runtime was k8s. One of the biggest issues were when something broke in production, none of the people couldn’t go to the container, check the logs and understand the failure.

There’s one situation where I think makes sense to hiring without a test: if the company has the resources and money to provide levelling training for all new hires with no exceptions. I do not know how practical it is.