Changes to the data in your sheet—changes to cells, adding or remove rows—are synced to apps within three minutes, although sometimes these changes will happen immediately.
Changes to the layout of your apps—changing components, themes, or other settings—can take up to 10 minutes to appear in existing apps, but should be available immediately for new users.
Changes to your app icon or splash screen often will not appear in existing apps unless the app is reinstalled. Android and iOS save your app's icon and splash screen when you add the app to your homescreen, and often will not refresh until the app is re-added.
Changes that are added within the app sync back up to your sheet in seconds.
In free apps, Glide refreshes your app data from the spreadsheet whenever the spreadsheet is manually edited. Therefore, if you use formulas that produce different values at different times without requiring manual edits, such as
GOOGLEFINANCE, your app data will not stay up-to-date.
Background Refresh, you can tell Glide to periodically refresh your data from the spreadsheet, no matter whether there was a manual edit or not, so those formulas will stay up-to-date. This is Pro feature.