The NEC requires some things only if the Authority Having Jurisdiction (AHJ) requires them; others are just optional
The NEC requires some things only if the Authority Having Jurisdiction (AHJ) requires them; others are just optional. Don't exclude these from consideration simply because you "don't have to" do them.
Why? The NEC isn't a design manual [90.1] and doesn't provide engineering guidance beyond what's adequate for protecting people and property from the hazards arising from the use of electricity.
An example of where this matters is the idea of feeders sharing neutrals — a practice the NEC permits [215.4]. Today's high harmonic loads in the typical commercial or industrial facility make this practice unacceptable from a performance/reliability viewpoint.
Another example follows right after 215.4. If the AHJ requires diagrams of feeders, then you must provide them (with relevant details) prior to installing the feeders [215.5]. The implication is that you can skip the diagrams if the AHJ doesn't insist you produce them.
The "justification" for not documenting the feeders is supposedly to reduce costs. In reality, it raises costs dramatically. Sooner or later, you will pay for that documentation. The worst, and most expensive, time to pay is when production sits dead in the water while techs try to decipher the undocumented distribution system.
"Saving money" by relegating design to mere NEC compliance is an exercise in false economics. Always consider the costs of not implementing reliability or operational considerations.