If saving battery life and data is your top priority, you can turn off Background App Refresh altogether. Background App Refresh allows suspended apps to check for updates and new content while they're running in the background. That way the next time you visit that app, it's updated with the latest information.
To completely turn off Background App Refresh, open the iPhone's "Settings" menu, tap "General," and choose "Background App Refresh." From there, press "Background App Refresh" and select "Off."
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