It has ZERO compliance with any Electrical Regulations nor with nodal current law. Never follow this guide, you have to use the same wire gauge (aka mm2 or AWG) for Live and Neutral in 1 phase system. As they suggest - using 3 Live to and 1 Neutral back - can cause overcurrent on the Neutral wire and because the overcurrent protection switches are in the Live section, it will not be recognised thus can cause even fire.
