I used the T5B flight connections on October 24th, landed around 11:45 AM and had a connecting flight that usually departs from T5B at 3:00 PM, the person checking boarding passes was initially skeptical about letting me through as the gate number for my departing flight wasn't announced yet, but let me go through security after I mentioned I wanted to use the T5B lounge and after making sure my boarding pass scanned without any issues.