By default, SheetDB cache your API data for 15 seconds. You can change this period in API settings. Cached data guarantees the fastest response time and bypassing Google's request limits.
When the cache is enabled, changes to the spreadsheet are not reflected until the cache expires or until changes are made to the spreadsheet using the SheetDB API. In the API settings under the cache tab, you can see what is in the cache and you can request to load or refresh the cache.