What about a transit in HKG of less than an hour?

Looking at CX983 to CX725 which on one particular date gives only 55mins on the ground in HKG

55 minutes is fine at HKG.
Of course, if you first flight is delayed by 30 min, that is another story.

thanks mate! that's reassuring

JOOI, is there a cutoff for the number of remaining minutes, for a ground staff to be arranged / standby upon deplaning for the transit?

There are ground staff waiting for the pax with tight connections. Should be no issue. If staff are waiting for you, there are one of two realities: either 1.) you're pretty much guaranteed to make it (since they'll call ahead and the gate will be kept open for you, while the staff escorts you through transit security to the gate to ensure you arrive), or 2.) they've decided on your behalf you're missing it. If nobody is there move quickly but that means they presume it's no issue for you to make it easily. It's not like where you need to run a thousand miles an hour through the airport and your speed determines if you'll make it or not, which is common at other airports but not HKG with CX.

Even if you're 35 minutes late (late to the gate not touchdown....landing on the north runway now makes for some atrocious taxi times to the gate), I expect you'll make it. I can't think of another airline I fly or major airport with such seamless connections for such a large international airport.

And the checked bags usually make it too.