I think we are answering simply when you are looking for a more comprehensive answer. Inductive heating is a result of two different phases, or a phase and a neutral being separated with metal in between. So, all phases and the neutral must be run in the same conduit together. When runs are parallel each "set" consists of one conductor of each phase and the neutral. There is an exception that allows us to group phases together instead, but only if the conduit and the box, are non-metallic, or a slot is cut in the metal box between conduit entries. When you are putting all of the phases and all of the neutrals in the same conduit you prevent the induction per the code.
