I don't disagree with you re the earn/burn rates. I am fortunate that most of my travel is point to point (ie SIN-MEL) so I rarely have to contend with the issue you face. However, I do SIN-LHR a couple of times a year and I don't think I have ever seen upgrade availability straight thru.

At the end of the day though, I would rather the upgrades clear (even segment by segment) than not at all and be stuck down the back...

Upgrades as far as Skywards miles goes has always been high - 30,000 miles between SIN-MEL is a lot for a 7-hr flight (when it's 25,000 between LHR-DXB). And I don't understand SIN-DXB at 32,500 (when it's actually shorter than SIN-MEL) distance wise.