As a free tool, we love Data Studio. However, it does have system limitations that you need to be mindful of when you are working with large data sets. 

1. Queries will time out after 6 minutes. 
2. Data is stored in the cache for 12 hours (you can check freshness of data in the bottom left of your dashboards in view mode. (see image below)
3. You can refresh manually, however you must be able to edit the report to refresh. 
4. Occasionally you might get this error "Service invoked too many times for one day: urlfetch." This means you've been using Looker Studio too much today- come back tomorrow when your allocation has refreshed. (This is set by Google)