Yep, been there done that. Actually had to do it twice during our B2B2B cruises this year (31 days on Rotterdam). Very long, very boring (although the guy in charge of the transition did his absolute best). Gather in the main theater, wait and wait for everyone to get there, and then exit the ship. Go through the face recognition screening, wait and wait again to reboard.
We're doing a B2B in 2024 and already booked a Fort Lauderdale shore excursion. Fool me once.