My experience

yyz - lhr forget about it, seems to never clear with moderate success in the past....am migrating to other carriers as the year continues

asia i use other carriers, same with middle east so no comment

But on myriad domestic/north american routes i use to to bat a thousand, especially to the southwest......this year i am finding that i have to be far more flexible in dates and even airports.

So I would have to agree with OP. In fact to/from YVR is 0%!

I will be attempting some Delta flights in the near future as I have been given 'gold' status there and i have heard on here that upgrades are fairly successful if not almost 100%......we will see.

PS, i have also noticed that in the past J class had many open seats and now it is always 90/95% full (great while it lasted but completely understandable )