The "first come first served" vs METRON/CTMS order is an ongoing debate. Sequencing as they come is easier for ATC (which means safer and less messing a/c about), but gives companies no incentive to follow METRON, and in fact punishes those that do. Ph flows do seem to "deprioritise" early a/c, but it can make life interesting on arrivals.
I have lost count of the times I have been slowed after the feeder fix and then arrive at Woora with nothing between me and the threshold, that is 15nm space infront.
Possibly you were being sequenced behind a 24 landing?