I work in public transport, on country commuter trains. Our roster allows for a finish time 45 minutes after the train is meant to get in, and we're supposed to restock the food service if we have time. If the train is say, 30 minutes late, we just go home. If it's an hour late, we put in for 15 minutes ot.
Previous boss insisted we stick around even if the restock was done and there was nothing to do, sometimes standing around for half an hour. Current boss is cool if we leave early s'long as the restock was done.
Ot is actually down with new boss because most of us won't bother to put in for less than half an hour. Train is 2h late – yes, we'll put in for that. But not 15 minutes. Because we know we're still ahead. We put in for everything with old boss because they made us stick around and twiddle our thumbs.
It makes me think what other places would actually make more/lose less if they used common sense and let the staff go early if it's not actually going to affect them.