Report problems in Service for specific users (errors in visuals, incoherent data in charts, ecc)

if you go to this that holds the white papers, you will find a document called https://docs.microsoft.com/en-us/power-bi/guidance/whitepapers

Planning a Power BI Enterprise Deployment

it gives some details on the different refresh aspects, you might want to download the whole doc

Package Refresh (File Level) Description
A package refresh synchronizes a .pbix or .xlsx file in the Power BI service from OneDrive or SharePoint Online. It does not run a data refresh from the underlying source data—it only copies the dataset out of the file and into the Power BI service. It also reflects any changes made to the reports in the .pbix file. How Refresh Is Handled
File-level refreshes are handled automatically by the Power BI service, approximately every 1 hour.

Cached Tile Refresh Description
Dashboard tiles display cached data, to ensure performance is optimal. The cached tile refresh updates the cached data displayed by dashboard tiles. This is useful after a data refresh has occurred to bring the dashboard tiles up to date. How Refresh Is Handled
There are several options for refreshing cached tiles.
Automatically by the Power BI service:
• After data refresh for imported datasets
• Approximately every 1 hour (or as specified in the dataset properties) for DirectQuery and live connections datasets
Manually:
• Refresh option from the menu

Cached Visual Container Refresh Description
The visual container refresh updates the charts, graphs, and tables which have been cached in reports for performance reasons. This is useful after a data refresh has occurred to bring the visuals up to date. How Refresh Is Handled
There are a couple of options for refreshing cached tiles.
Automatically by the Power BI service:
• The visual containers are usually refreshed automatically once a data refresh operation completes
Manually:
• The Refresh menu item at the top of a repo