This worked out in my favor actually. I'd booked SFO-IAH-SYD on a Thursday (with a 40min layover in IAH) as IAH-SYD had much more PZ space, they first had rebooked me via LAX and then I called up and they opened space in PZ for me on the non-stop. Net-net pretty happy, though I was sort of curious to try out the 17hr flight, I like these long flights to catch up on my reading without people disturbing me