Hi Pradeep,
Out of the box it runs every 15 minutes but you can always have it set to 30 min intervals or as often as you would like. One thing is that an ETL will not run over another. Meaning if you have 15 minute intervals for the ETL to run, if for some reason it runs for lets say 3 hours, then another ETL will run after that on a 15 min interval again. This is how SQL Server Job Agent runs things.
Regards
Jitesh