I have done pretty elaborate Oneworld award tickets and it's only taken me about 15-20 minutes of hold time with an agent. That's because I already know what flights have availability in the class I want (thanks to either Expertflyer or the Qantas website) , and I'm armed with all the information beforehand. I think the agents get a bit irritated that I know more than they do, but it does help them out in the long run.