Is this some sort of polling ?

yes

End of the day, we are just worried whether this will hog resources compared to a web-hook ? Any ideas (edited)

No need to worry, it pulls every 30 sec, and this is negligible (as a comparison any task will at least send a write request every 30 sec, if not more)
Actually webhooks might be more taxing on the server, as you need to always have a webhook up (i.e. wasting a socket ...)