When I went on weekdays (5/2) during the GW, most ...

When I went on weekdays (5/2) during the GW, most of the restaurants on the 6th floor had the last order of lunch at 14:00, and after that it was not until 17:00 or only snacks. I don't know the hours of operation on weekends and holidays, but you may need to be careful about lunch and so on.
The rooftop can only be reached by elevator, so it's just a long queue right after opening.