We always had that question about locking doors when we gave walkin service till 4:30. If someone came in at 4:25 they might be quick or they might take a long time. Then everyone was late getting out. Our management solved it by having two or three people start at 8:30 and work till 5:00. The 8:00 people left at 4:30. The door wasn't locked until 4:30.

I would think a store who advertised Open till 9:00 wouldn't lock the doors till 9:00.