From my POV conditioning is more about HR than anything else with muscular endurance a secondary aspect.
Whatever I'm doing I want it to be whole body, hit 80-90% HR max, and hold it at that peak for about 20 seconds, rinse and repeat. Anything that gets it there fairly rapidly isn't anything you can do for extended periods anyway, but a prime goal (in my case) is to condition the glycolytic system at the mitochondrial level. How much of this is the focus or incidental can be managed by tweaking the rest intervals, although too short an effort or too much downtime between efforts blunts the glycolytic improvements.
I don't really consider my jump rope HIIT to be conditioning in this context as there just isn't any real muscular loading happening.