I'm with you
gaia, although my flying (150 international flights last year on top of more than 100 domestic) is spread over several airlines. My upgrade success has been minimal on QF (other than getting F seat on 2-class flights and J seat on 1-class flights due to equipment). Most of my upgrade credits expired unused and no points upgrades have been successful.
Then again, most of the time on QF I am already in the front cabin - either all economy flight or 2-class flight in business.
This isn't unique to QF. On NZ I also have top status and also struggle to upgrade. Some years I am unable to redeem my complimentary upgrades, others I have only used by gifting to others on short regional flights - a bit of a waste of an upgrade that can be used longhaul but better than getting no value from it. The routes I most want to upgrade are virtually impossible, and even getting paid business class is near impossible unless booked sufficiently early.
QF & NZ have in common a handful of routes with far too little capacity in the premium cabins