I understand the clearance limits system in the US means minimum work for ATC when the dung hits the ventilator. Instead of the "general holding" button going 'ding', the flow screaming "hold fakkin everybody" or trying to believe Maestro's yellow numbers the pilot is given a clearance limit, and when he gets there holds.
Over there everybody is an approach controller managing sequences all over the shop.
I don't see how this can be more efficient, most of the work in holding is setting up aircraft in trail so they can be shuffled into approach order and stacked when they get to the fix. Do they set everybody up vertically for the fixes?
I guess we'll all learn about this in stage 3
