It’s not challenging, needlessly (as in nobody is behind you trying to go faster) is just that, unnecessary. The whole point is that you move over if someone is behind you.

People swinging back and forth to left and right even though there’s nobody behind them on the left most lane just causes a hazard for others without any benefit. I think it’s just their mind going “well someone said it’s for overtaking only so I must move back to the right” without really thinking it through.

And good drivers pay attention to stuff happening around them. If you as a rule are zoning out, I have bad news for you lol