Not being able to leave if you work well and are done by 5 sucks no matter what. But can you do other things especially in the last 1/3 of the day when I assume

Not being able to leave if you work well and are done by 5 sucks no matter what. But can you do other things especially in the last 1/3 of the day when I assume people will be more tired? Or if you’re not really working, is your only real option to just lose that time entirely?