Is it better to workout hard briefly and then rest or workout gently more often?

I have read somewhat conflicting anecdotes about how hard/often you should workout for peak fitness/longevity.

Some say you need intense activity, which requires a lot of rest.

Some say you need continual movement, which would not allow for intense activity.

Extreme examples of ultramarathon runners and powerlifters potentially doing more harm than good are counterbalanced by what we see in nature, which is long bouts of inactivity/rest when "exercise" is not required.

So, for example, would it be more beneficial to lift heavy weights and do HIIT training 3-4 times per week and then relax the rest of the time? Or to do something like light calisthenics/walking multiple times throughout the day?