HIIT interval durations and intensities

Getting ready to commit myself to daily physical conditioning after a vacation of a few weeks from such, I reviewed what I had read about High Intensity Interval Training (HIIT), read some more about it, and put the results into a table:

HIIT Work/Recovery Cycle Patterns

In a 2008 paper, Mark J. Smith Phd, praised HIIT training as more effective and also less time-consuming compared to moderate-intensity continiuous training:

"... sprint interval training (SIT) is also referred to as high intensity interval training or HIIT. It is of major importance that health care professionals...get thoroughly educated about the superior health and fitness benefits of SIT, or “burst” training, as compared to low to moderate intensity continuous training (LMICT)...most people still believe that to develop a healthy heart and to lose weight, the best mode of exercise is long and continuous “cardio” exercise, which, inherently, requires a significant investment of time...lack of time is the number one excuse given for not complying with an exercise program..."

High Intensity Interval Training or HIIT consists of patterns involving alternations between short period of extreme and effort, and short periods of rest or low-effort activity. Many different recipes are prescribed, which differ in terms of; the amount of time occupied by high-intensity intervals, the time-length of low-intensity intervals, the intensity of effort during high-intensity intervals, and the intensity of effort during low-intensity intervals.

So far, I've found only one webpage that sets forth a formula for determining length and intensity of the various intervals, based upon individual characteristics of the person doing the interval training:

"...your high intensity intervals should be performed at an intensity of roughly 90% of VO2max (this correlates to approximately 95% of maximum heart rate)...The length of each high intensity period should be roughly 75% of the maximum amount of time that you could last at this intensity before fatiguing... If, for example, you can last for 200 seconds ... before fatiguing during this trial period, then your actual high intensity intervals should be set to last for 150 seconds each...If you are a beginner, set your rest to high intensity interval time ratio at 2:1 (i.e. your rest interval duration should be twice that of your high intensity interval). If you are well trained then you will ideally have interval time ratios of 1:1 or even 1:2...During your rest intervals, you should carry on your exercise activity while reducing your intensity level to approximately 70% of maximum heart rate...Set the total number of intervals performed over the entire workout so that the total time spent at high intensity equals between 20 to 30 minutes...Start and end your training sessions with a rest interval...Since these types of training sessions are fairly demanding, you should perform them no more than 2 or 3 times per week..."

Of hundreds of web-pages I looked at so far studying HIIT, the source of the quotation above, is the only one, that gives a formula whereby the duration of the high-intensity and low-intensity intervals, is based upon a characteristic that can be quantifiably measured in the individual doing the exercise.

All the other web-pages: speak simply in broad generalizations, such as, this for 'beginners', that for 'intermediate', this for 'advanced'.

In general I found the following ranges in terms of duration and intensity of high-intensity and low-intensity intervals proclaimed: duration of high-intensity intervals, 10 - 240 seconds; intensity of high-intensity intervals, 85%+ of max effort; duration of low-intensity intervals,  4x to 0.5x duration of high-intensity intervals; intensity of low-intensity intervals, rest to 70% max effort.