Frequency of allowed /delta calls to detect changes

I'm using the /delta endpoint (via the PHP SDK's getDelta method) to detect when any changes have been made in a folder or any of its children, grandchildren, etc. It seems to work well. However, in the API documentation it instructs to, "...wait a while (at least 5 minutes) before calling getDelta again". I'm running my code on a linux-based server and wish to deploy it as a cron job running more frequently than every 5 minutes, so that I can be notified rather quickly about any new uploads. If /delta is intended to be called at most once every 5 minutes, is there another way to achieve the same goal easily with a lower time interval in between checks?