For Manhattan NY a few days ago, once I got past security which only had Haven and not Haven lines and they didn't check boarding times, I used the casino line. The usher didn't check my boarding pass at all. The sign didn't say Pearl or above. I couldn't tell if the agent did anything with the casino status because they processed the Latitudes priority and casino lines together.
But after that, we still waited to board the ship and casino seemed to be behind Latitudes people. It was kind of a ship show on this boarding.
I don't know how they do it if many more people are there and everything's backed up.
Next time I'll....
Ignore the boarding time and get there early to get through security ASAP.
Use the casino line if it seems shorter than Latitudes (I'm Shapphire).
Board the ship with the group that goes first. (Casino or Shapphire but I'm guessing Latitudes).