Originally posted by David Záleský:

Tom Wyliehart
Players are allowed to sit at their tables, without filling out their slip, so long as time is left in the round. Once time is up, they need to fill out the slips.

Is there any written policy supporting this statement?

I'm not aware of one. I have, in the past, required some particular players to fill in and hand over their results slip to me promptly and with plenty of time left in the round, when their actions tended to suggest they may have been about to improperly determine a winner.