This differs from supplier to supplier. Every supplier update their data on different frequencies. At the Vervotech side, we call supplier APIs on different frequencies based on guidelines provided by each supplier. For eg. for Expedia, we update the inventory every Monday as we know they update their inventory on weekly basis.
If you want to check the history, you can navigate to Providers Content Processing History on your Vervotech Client Portal account. On this page, you will be able to see the entire history of the data with respect to inventory getting updated for all the suppliers enabled for your account.