Currently (and this changs with the winter schedule), UA flies a 744 on a LAX-SYD-LAX-NRT-BKK-NRT-LAX schedule so the 744 sits on the ground in BKK enough to do this treatment, although I have no idea if it's actually done the way DL is doing it. From SFO, I'm sure they do it while the plane is on layover in either SIN, SGN, or PVG.