Informally this used to happen fairly frequently, at least for status passengers, but over the years it has been stamped out (except on LCY longhaul from time to time). The only recent occasions where this has happened has been when there is a noticeable delay in departure, typically waiting for some bags to be offloaded "as some of our customers have decided not to join us today". Having said that, it doesn't make much difference, the bottleneck on service delivery doesn't appear to be order taking. And I guess ordering Special Meals probably gets rapid delivery on the whole.

However my take on the lates to HKG and SIN is that for most passengers, even in CW, it's a big event which doesn't happen often. So normal rules get suspended and in the context of the big time zone changes most people don't try to rationalise it too much. Now regular passengers will perhaps be aware of the ramifications in terms of jet lag, happily there are lounges and noise cancelling headphones to get around this.