According to International rules disagreement over life/death causes resumption of the game then should two passes be made again immediate scoring ensues. Thus one is forced to play out the game until every group is either removed or has two eyes. I think this is a (slight) waste of time and a bit unelegant. I would prefer to cut the game short by adding additional negotiation phases. Aside from the agreement phase being fun there is no risk of neverending dispute as the life of at least one group is solved in each phase.
Furthermore this has the advantage that in effect 4 passes are necessary to end a game. Thus it is guaranteed that there is no KO-Fight going on and that both players agree on the statuses of the groups and that the game is indeed finished.