If you don't mind me asking, what was that residential NEC stuff did they have you deal with?
I typically work on industrial megaprojects as lead electrical engineer. That's the cool part - big generators, motors, VFDs, transformers, and all the fun control systems that go along with them. The money-making portions of a facility like this (think refinery, generation stations, liquefaction plants) are way above your average local electrical inspector so they fall under the jurisdiction of FERC, and as such I am the authority having jurisdiction (AHJ). So basically I can do what I want. I mean, we still follow the NEC generally for things like grounding and cable ampacity and safety protocols, but beyond that it's "engineering judgement". If I need to install a new 30MW feeder line for a VFD driven synchronous motor I don't need to consult any licensed authority, I can just do it.
HOWEVER, when it comes to the portions of a facility that are considered "occupied" in the eyes of OSHA, then the local AHJs get a say. These portions of a site are generally the administrative buildings, any temporary construction trailers, control rooms, things like that. Small-scale commercial stuff with HVAC, 120/208V DPs, lighting transformer loads, etc (very similar to residential). This is where it gets miserable (IMO at least). Everything needs to be done by the NEC and there are always local AHJs/inspectors that need to prove they know the code better than you and it's often very obnoxious. The NEC part is pretty easy once you do a couple jobs and you've memorized the feeder/secondary tap rules, bonding vs grounding, etc...and most importantly after you've taken your local AHJ to lunch a few times and get a relationship going with them. Permitting is always a wildcard as are inspections. Depends on your local authority. Whatever it is, mentally stimulating it is not, at least not to me. It is rather useful in a practical sense though.