HIIT is a powerful method to help shed fat, burn extra calories and put on lean muscle. The mere fact that timed intervals give an exceptional outlook on the guideline of how fit you may not always be the greatest factor. Certain intervals such as tabata style or 30/30 can be really good however; when it comes down to the level of intensity to rest ratio its only worth its weight in gold on what hits that level of intensity and the need to rest.
If you're doing ultra intense exercise while only resting for a very short period of time that can screw things up especially on the Central Nervous System. No matter how good of shape you're in a long rest period of very intense training is more beneficial than you'll like to believe. A lot of trainers depict heavy challenges and takes on a general assumption of how intense a workout should be and for how long. Funny thing is unlike many things, a lot of trainers or coaches don't take into consideration about a person's body type and level of fitness to give them something to realistically start with and giving them an idea of how to use their full potential.
There are many pros and cons to interval training but an ideal way of timed intervals using specific exercises such as burpees needs to looked at from a certain perspective on how to keep energy going and not depleting the muscles to where they're so broken down with little recovery its more of a disaster than an achievement. I do prefer the 30/90 Protocol on HIIT because its the perfect blend of intense exercise and the ability to recover so you'll be strong enough for the next set. Burpees in this fashion are awesome because the exercise itself generates powerful entities in the body when used properly and using the best form possible with enough intensity to go hard. During the 90 second rest period instead of just standing there, use the time for Active Rest meaning use deep breathing, light stretching, marching, anything with far less intensity to bring things down but still keep the blood flowing.
Use this protocol 2-3x a week for a month and see what you get out of it, your body could change at a faster rate because you're getting hard exercise but enough rest to gain oxygenated blood and have the muscles build a solid foundation to grow efficiently.