I’m trying to work my way up to doing HIIT. Not quite there yet. If you do HIIT right, you should only do it for no more than 10 minutes, and feel like you can’t possibly go on any further.
If your output is high, your time can only be short.
When I do sprinting for exercise, I do a total of 8-80 yard sprints. This is after warming up. I’m concerned with maximum output, so I take 3 or 4 minutes in between sets. I’m training for Masters T&F, so speed is my goal.
You could check out the Tabata protocol about HIIT.