I believe that the Great Massacre scene was contrived to provide maximum visual impact--and logic be damned. How could Tess not know? Sure. How did Cicci and Clemenza get back to the Mall in Long Beach, Long Island, so quickly after whacking their targets in NYC? How did fat Clemenza survive after climbing all those stairs to blow away Stracci in an elevator car--and how did he know which floor to stop on? It goes on and on...but it was a great scene.