JFK has always been frequency led rather than capacity. That’s why BA operate so many flights ex LHR and don’t consolidate and use A380’s.
Norwegian needs to try and match frequency where possible.
Frequency for time sensitive business fliers between LON-NYC meetings. BA use B744s with 86J seats, i.e. Y starts after door 4.
Norwegian have almost zero focus on long haul business travellers, no lounge offering etc, they're price led. Hence frequency is not a must.