Hi Geff89,
The 3 year re-application rule applies to the flying component of flight screening only, and not the OSB. They never used to give you another chance to complete the flying again but this has changed.
Once you complete the OSB and are recommended, your file is in the pool for 1 year. After that year is up and you don't get a letter of offer, your file then gets sent back to DFR. To get your file back into the pool, you will have to complete the assessment day and the OSB (not the flying component of flight screening) again. You may have noticed at Tamworth there were OSB only candidates that rock up on the day before the group activities and OSB start. I know this because I was one of them
Your flying score is retained for 3 years, but I think you can keep it for longer if you did well, or complete it again after the 3 year waiting period is up for a better score. Hope this helps