It&#x27;s &#x27;5x&#x27; for two reasons: (a) that&#x27;s a reasonable target for how many times you might have to ask it before you hit a root cause and (b) the &#x27;five&#x27; is meant in a more metaphorical sense - you&#x27;re meant to ask until you hit the root cause, but &#x27;five&#x27; is catchier.