Some people clock out at 5. Some clock out at 3:30 and stay in the building. Everyone can tell.

There is a difference between leaving and having left, and the people around you can feel which one is happening. Checking out early while still standing there shows in how you answer questions, what you notice, and whether you spot the thing that needs doing. Nobody has to keep score for it to register. It lands on whoever is beside you, carrying the part you stopped carrying.

If you are going to be there, be there properly, and if you are finished, say so and go. In the last half hour, find one thing to complete.