[zhte415]

Perhaps a different angle.

If done at 4pm, just leave, do something else, volunteer a project. No need to be seen to put in 'required hours;. Delivery is important. If anyone sticks around for required hours they're being dishonest with their team about their capacity.

For overtime, a good manager depends on honesty of their staff to gauge their capacity. A staff member that sticks around until required time doing nothing but pretending they are doing tasks is being dishonest about their capacity.