Traditionally, a key duty of senior NCO's has been to babysit (in effect) young naval officers, when the latter are in command of critical things. That's both to prevent expensive noob goofs, and to have a seasoned leader on hand if the "routine" situation suddenly jumps out of the young officer's limited competence zone.

Might anyone be familiar with the Norwegian Navy's traditions or practice in this regard? From the article, it sounds like the "young and relatively inexperienced" OOW was probably the most experienced (years of service at sea) person on the frigate's bridge. With two trainees under him, who he'd have needed to keep eyes on.

Can’t speak for the Norwegians but that is not how at-sea watchstanding works in, e.g., the US Navy. The OOD is the captain’s delegate in operating the ship. In peacetime steaming, there may not be another khaki (officer or chief petty officer) on watch who is qualified to stand OOD - the JOOD/JOOW is typically a trainee, and the CIC watch officer is often a non-OOD-qualified junior officer or chief petty officer. They can and should all provide support to the OOD but usually nobody is available to babysit or step in. All of the babysitting should have happened before the OOD ever got their OOD qual.

Which btw tells you what has gone wrong in many of these situations: the OOD was given a qualification they were not ready for, because not having enough OODs means the actually-qualified OODs will be standing port/starboard watch and be exhausted all the time. COs and XOs give the weak OODs quiet steaming watches they think will be easy, but a shipping channel can get busy earlier than expected and everything can go to shit really quickly.