Employee A: I have an event that I must attend and cannot inconsequentially avoid.
Employee B: I want to go home and relax.
Employee B: I want to go home and relax.
As your co-worker or your boss, why do I care in the slightest whether you're going home to take care of your kid, to smoke a bowl and watch a movie, or because a new video game was released that day?
If A, B, and C are all getting their work done in the time that they are working, I think equally of the three of them, as subordinate, peer, or supervisor.
A, B, and C should all just leave at a regular, reasonable time. And sometimes each of them has reason to leave early, and doesn't need to justify it.