MediaggChecking for new episodes
How often subscriptions are checked, what happens on mobile data, and refreshing by hand.
A subscription is only a subscription because Mediagg goes back and asks whether anything new has appeared. How often it does that is under Refreshing in Settings.
How often
Check for new episodes offers Never, Every hour, Every 3 hours, Every 6 hours, Every 12 hours and Every 24 hours. The default is Every 12 hours, which suits most podcasts: a show that publishes weekly gains nothing from being asked hourly.
Never stops the automatic check entirely. Your subscriptions still refresh when you ask them to.
On mobile data
Refresh on mobile data is the second row, and its own subtitle says what off means: Off means feeds are only checked on Wi-Fi.
Refreshing is cheap — it fetches the feed, not the episodes — but with a large library it is not nothing, and downloading has its own separate setting. See Automatic downloads.
By hand
Pull down on a list to refresh it. A single subscription can be refreshed the same way, by pulling down on its own page.
What a refresh actually does
It fetches each feed and compares what is there with what you already have. Episodes that are new to you arrive marked as new, which is what the New chip under Subscriptions lists and what the New Episodes shelf on Home shows.
A refresh does not download anything by itself. Finding an episode and fetching its audio are two different things, and the second one is off unless you turn it on.
When a refresh fails
A feed that has moved is followed automatically. A feed that answers with an error keeps the episodes you already have — nothing is removed because a server was briefly unreachable. See A subscription will not refresh.