Complex sentence: The questioning for this example could be taken further to a sixth, seventh, or higher level: the "five" in 5 Whys is not gospel, but five iterations of asking why is generally sufficient to get to a root cause.
Split into simpler sentences: The questioning for this example could be taken further to a sixth, seventh, or even greater level. This would be legitimate, as the "five" in 5 Whys is not gospel; rather, it is postulated that five iterations of asking why is generally sufficient to get to a root cause.