For me it's a 50-50... It did save my time a few times, but of course also had the experience of already at the airport or on way to airport... Worst one was just got on taxi for a minute (was T-75 mins already... Still at Wan Chai)

Actually I believe this is related to the backend system of CX and from what I experience earlier it's still very manual...

HKG-PVG, originally on KA, but due to flight control flights keep slipping departure... Found the FIDS screen at the airport and the HKAirport app, the next flight after accounting the 40 mins check in time was a CX one with a new ETA at T+60 (T = STA)... So rushed from aisle H to B and asked if I can switch to the CX flight...

To my surprise the counter said in the system the flight still showed on time. Counter helped me to call gate to confirm the flight is still at gate and confirm the new ETA then helped me to call flight control to get a seat... and told me "maybe they don't have people to update the system yet"

So at T+5min I got an interesting boarding pass showing boarding time T-35 and departure time T...

And after seeing all those CX Secret posts I seriously doubt what CX IT is doing...

(off topic sidenote: Of course on board I am no one... And on the boarding pass my status is not DM/E above my membership number, but CXDM at the place where CXAM / CXGR is normally shown... Interesting...)