That's a fair assessment I think.  It clearly depends on when the roll is done.  But SOMETHING has to get zeroed.  In this example, there's time to have a straight line after the last maneuver, roll, and still draw a long straight line prior to the next (2 half rolls opposite) though I would have probably thought that he just started the half rolling early and forgot to roll opposite directions, only to do it again. lol.