Case 1: the campaign is scheduled in local time
Campaigns scheduled to be sent at specific time, in the timezone of the user (see "Local time"), will run for 24 hours. This will make sure Batch delivers the message at the right moment to your users.
If you set your campaign at 8AM local time, users based in Paris will receive the push notification 6 hours earlier than users based in Shangai. During these 6 hours (and more), the campaign will be live.
You can check if your campaign has been set on local time in the Review section of your campaign's details.
Case 2: recurring campaign
You can create push campaigns that repeat at specified intervals based on your users' local time or on global time (UTC). These campaigns will be displayed as complete once the end date has passed (if you specified one). You can also stop them manually if needed.