Ditto.
i have had no failures to clear in the last few years. H4nce have a rosey view of the process.
But I am a realist, if I want J / PE to North America I either book into R class 6-9 months ahead or pay for it and don’t rely on an upgrade clearing.
I have had multiple upgrades clear to HKG, Japan, Perth, Islands, London ex-LAX, but I don’t gamble ex-AKL/rtn to North America - if you want it, pay for it or book in to R.