When limits on a debate are imposed, it's usually when the open debate has adequately explored the breadth and some of the depth of all sides of the argument. The speakers proceed to argue their case for X minutes. Debate is closed. A vote on the issue is usually taken unless a motion is made to extend debate. The e-mail must be submitted within 24 hours.
Debate is closed.
A motion to the previous question would now be in order, unless someone wants to extend debate or the limits on the debate. For example, one could motion to postpone an item until a meeting in Santiago. I still think it should be kept, because it requires agreement. Without agreement, this could be used as a delaying tactic, and that would be bad. The alternative would be that nothing could be postponed.