Check your grammar now! : intense or paroxysmal excitement; especially : the rapid pleasurable release of neuromuscular tensions at the height of sexual arousal that is usually accompanied by the ejaculation of semen in the male and by vaginal contractions in the female.
So, even though you may have only burned 250 calories during your HIIT workout, the total calories burned after will be far greater. Those calories, plus the 250 burned during the HIIT workout surpasses the 400 burned during the slow, steady-state workout by a LONG, LONG way.
If you do it as you suggest, you will not be doing HIIT so I am not sure it matters. If you want to do real HIIT, then do it 3X per week on alternate days plus weights on alternating days. Take one full day off where you don't do much. HIIT will tell you how many minutes, not the other way around.