I've had 1 upgrade with SQ, excluding the TPPS birthday upgrade.

From Y to PE on SIN-HKG, I think at the time due to an aircraft swap in one of the old config A380, where the swapped aircraft had less Y seats than the one we originally booked on. I saw several other passengers get upgraded too, so I think it was definitely due to operational requirements and not out of good will. I think I was only KFEG at the time.

Fast forward, not sure how many total flights I've taken on SQ but I flew every week for a good chunk of my life, zero upgrades from Y to J or J to F.

In my prior life I was flying a lot with CX, I would get upgraded maybe about 50% of the time intra-asia and 10-20% of the time on the longer hauls. But SQ has always been a more preferred carrier for me for the consistency as I never understood the aircraft lottery with CX, where to provide that level of inconsistency in the J hard class product is just odd for a carrier that does so many other things right.

Haven't flown CX in over 5 years now so i've no idea if the situation is different now...