I have to laugh at HST. Really three whole body routines a week is something new? I'm glad new light was shown on effective basic training though. Training the whole body in one shot is sometimes called a beginner routine. Nope, it's the absolute hardest way to train.
What makes it great is that it trains a body part three times a week and some weeks if you just get it done twice you are still moving in a positive direction. Looking at the HST site it point outs if your are doing a split training a body part once a week you might be doing six work sets a body part. In say a whole body training session you might hit a body part for two sets in one day but done three times a week you are doing six sets a body part. The HST site points out that it might be more effective to hit the body part three times a week instead of blitzing it for one day.
The whole body training routine was a staple in the 30's, 40's and 50'. Still had many followers in the 60's but fell out of favor once Dianabol made it's appearance. Tommy Kono the hall of fame Olympic lifter and bodybuilder was very adamant about training three days a week training the whole body in one session. Now elite Olympic lifters train 6 days a week but I bet as they get closer to the competition date they might have a better taper using three days a week. Then again who am I to suggest that? Tommy Kono did repeatedly.
I always had good success with a whole body routine but I found I found it leads to burn out pretty quick. It's a very hard way to train.
Some draw backs.
1. You can't train a body part with many different exercises. One or two tops a session. If you feel the need for variety you can change the exercises each training day or change them after a set period of time like every two weeks.
2. A training session can leave you devastated. Something you won't get with a chest day or a a shoulder day.
Some real benefits.
1. Your body tires a unit and fatigue isn't localized to just a body part trained. So with a whole body routine your train and rest the body as a unit.
2. Body parts don't work in isolation. When you sprint, box, wrestle or throw a basket ball in a hoop your body is working in a complete coordinated pattern of muscles working together. Why not train the body like that in one session? Think an athlete would benefit from an arm day in the gym? Nope, he certainly would benefit from doing power cleans, squats, presses, chins, dips and the rest in one athletic training session.
I typed too much. I heard there are naked women on the internet. I intend to find out if that's true.