Quote: " During single engine operation, once the fuel is within balanced limits, then the remainder of the flight can be flown with the X Feed Open and all Fuel pumps On".
T'aint necessarily so. This is a furphy put about in simulator exercises, because some older simulators typically will stay in balance when set as described above. In real aeroplanes, chances are that one boost pump will put out more pressure than the others. In some engine-out scenarios, one boost pump in one tank may also be de-powered, thus exacerbating an imbalance if X feed is left open.
Only exception to this with some types is in an excessively low fuel situation when the QRH may say to leave it open.
Bottom line - if the QRH says to close the X feed for landing, just DO it.