there's no 'correct' intensity - just like there's no 'correct' frequency - just depends on the athlete's goals.
what's clear tho, is at the edges of performance, there are gonna be trade-offs between highly frequent and highly intense training - unless you're a pro athlete, of course
for the large majority of peeps, i guess this distinction doesn't really matter, but since hn is about optimizing at the edges, i figured i'd mention!