Then you were lucky to find a check-in agent that was willing to bend the rules for you.
In years past it was certainly possible to do that. But not in recent times. I am not sure exactly when the 12-hour rule came in, but expect it was in the last 2 years or so.
I think you got tricked by QF/CX or whoever told you the rule. I did around 10trips in transit at HKG for > 12 hours and I NEVER had problem with the bags not interline. I don't think it is rules
Also if you do turn arounds, they can check ur bags to the final destination without sending them to the turnaround point.