Comment by falcor84

> The junior dev wont get half way through the day and tell you they've used up all their coding time for the month and will now respond with jibberish.

This issue manifests a bit differently in people, but I've definitely worked with people (not only juniors) who only have a few productive hours a month in them. And for what it's worth, some of those people were sufficiently productive in those few hours that it was rational for the company to keep them.