HIIT is great for cardiovascular development, but be aware that this develops your carb oxidation, and doesn't do much for fat oxidation. So many health problems are tied to poor metabolic flexibility, where your body favors carbs over fat. You develop fat oxidation, and metabolic flexibility, with long endurance, low-intensity exercise. Pro cyclists racing every day in the Tour de France right now are going mostly on fat oxidation at incredible power levels. They got there with mostly low intensity training (but lots of it, and some degree of HIIT). Here is a timely publication that goes over variables tied to fat oxidation (and points out how intensity deactivates fat oxidation): https://link.springer.com/article/10.1007/s40279-022-01727-7