I reread the question…sorry I missed the doesn’t include the whole party.
If it’s me and one player, 3~5 speak and response cycles. If it’s important, I take that player outside, give the rest of the table a 5 minute break, and I have a cigarette, while focusing on things.
If it’s half or nearly half… and it’s long… I break it up and have the rest of the party doing something.
If doing turns around the table at role playing speed…30 seconds to a minute to each player, keeps things in going. If your group has 3 gabby people and 2 that are just there to kill something…you have problems.