3hr15mins transfers get a 'Long Transfer' green tag at HKG check-in...

Bags make their next flight even with a 50mins connection, so I'd imagine they normally only tag 'rapid transfer' bags when connections are less than 1hr. Seeing how outports are very often running out of resources I'm not surprised that was the case for you.

Frankly, the tags more often than not don't really matter, they're more for show since bag status and member levels are embedded into the barcode/RFID. The handlers just scan and they'd be told which containers to put the bags in. That's what I gathered at HKG.