hello everyone
on Dec 2018 I attended the OD and I got selected to the 2nd round day (assessment day) but unfortunately I didn't get through it and they told us to wait 6 months to reapply again and to do not outsmart the system . there gonna be another OD here on Feb 2019 so my question is do i really have to wait 6 months to reapply or is it ok attend within those months

Yes, you have to wait for 6 months before you apply again. I was eliminated after the second group activity but then decided to visit an OD in another country just 3 months later. The recruiter told us " If you participated in AD group activities in the past and you decided to try again before the 6th month please walk away now." I decided to stay during the OD, I was selected for AD and I acted innocent but I got rejected at the height/reach test which was weird because I passed it during the previous AD. It seemed like the recruiter knew that I was cheating.
They freaking know stuff and don't care how many years it will take you to get selected.