Graduate Nursing Positions and Reference Checks

Hello, I live in Melbourne and I am currently awaiting results of my graduate applications. The results are released on October 15th. I have had news that my references have been contacted and wonder if this is significant or do the hospitals contact all applicants referees? I figure that would be a tedious process as some hospital interviewed over 500 applicants. Also do the hospitals contact the successful applicants on the day the results are released?

Thankyou in advance.