There should be a command that lets people call a supermajority vote to extend the round by 5 minutes. If it fails, no more votes that round, if it passes, it should be available again. This way rounds can be extended indefinitely if people want to have more fun in a classic round, or if it's survival and a large house got griefed and no mods are online and the round still has seconds left, etc etc. I don't see any drawbacks besides people being annoyed if they vote no and it passes.