Context, Pre-covid, I flew mostly CX, Gold status at most, sometimes Silver.
Some sectors that I would fly would be well serviced, but not extremely busy (HKG to MNL, HKG to TPE). On these sectors, my % of upgrade was pretty decent, over a 5 year stretch, I'd say perhaps 10% chance. mostly at gate.

I have since switched allegiances to SQ.
Have a SYD to SIN to MNL this month, and the reverse next month, and a SYD SIN TPE in Dec.

I have read in other places that people believe SQ to be rather protective of their premium products and thus dont give it, but from my experiences with CX, often they were oversold Y, and then bump up their regulars.
SIN to MNL in particular, I think the demand for Y is higher than premium classes, chances of Y being full to oversold is pretty decent, for those whom may have had comparisons with other airlines, what do you think of the chances with SQ?

I have Kris Gold, and booked in Econ Flex.