GoKawiilIt's convenient not having to open apps to keep them updated, especially if you have a lot on your phone. For instance, it's annoying to open your podcast app on the bus, only to find that the latest episode didn't download like you expected.
But you probably don't need automatic updating for every single app on your phone. And thankfully, it's a granular option. Visit Settings > General > Background App Refresh to review its setup. Tap Background App Refresh at the top to choose whether it functions on Wi-Fi & Cellular Data or only on Wi-Fi (good for saving carrier data). You can also disable background refreshing entirely by choosing Off.
Otherwise, you'll see a list of (nearly) all the apps on your phone here. While they may all be enabled by default, many apps don't need this permission. It's smart to keep background refresh on for any apps you use regularly or rely on for real-time information. I recommend leaving it enabled for apps that deal with travel, navigation, file syncing, reminders, productivity and similar.
Conversely, background refreshes aren't necessary for food or shopping apps, most games or apps for browsing websites (like Wikipedia or IMDb). If you barely ever open it, you probably don't need regular updates to its content.
While disabling apps here, be aware that disabling Background App Refresh does not suppress notifications. Even if an app isn't fetching new data in the background, it will still show notifications as long as you've enabled them and they aren't blocked by a Focus. In most cases, disabling an app's background refresh will result in, at worst, you having to wait a few seconds for new data to load. If you aren't sure about one, try disabling it and see how the experience changes.