Just to add regarding setting a time limit.

If a player is requesting to go to the bathroom or have a smoke, we should point out the event time limits. So if it's at a round end, “Hey do I have time for a smoke?” or between sealed pool registration and deck swap/building or at any point in an event, we should be telling the players what time they need to be back.

“Sure, but card pool registration will end in 5 minutes so be back by then”

or

“You have until X time to be back in your seat, if you think you have time then sure go ahead”