thats a little off, it should be farthest to closest in sequence. RightRear, LeftRear, RightFront, LeftFront. If you're still getting air, you might have air in your master cylinder bore which would require a bench bleed. This can happen if the reservoir went empty and someone depressed the brake pedal. If this is the case, get a bleeding kit, remove the MC, bench bleed it, re install it and rebleed.
Also, just to state the obvious, you ARE checking the reservoir every time you bleed a different wheel right?