Icontinually hear about people overtraining and folks in the gym thatspend hours and hours doing ongoing cardio(mostly steady state) as wellas even still more hours of weight resistance training. 

Honestly there just is no need for countless time put in.  What dothese people expect to get from all their invested time?  A betterbody?  Well if that is their goal they don't need to spend all their time getting it and should be spending more of their time enjoying it.

There is a time AND exercise amount that the human body reaches that it justwill no longer respond positively. Instead it will regress or notprogress. In my opinion if there is no progress then there is no reasonto do it at all.

After 45 min. of intense exercise certain hormones- such as cortisoland estrogen- are produced in large amounts and bring the body to acatabolic state which is a muscle breakdown environment. Yourtestosterone will greatly begin to decrease and estrogen increase. Thisis not a good thing.

If you spread your workout over a longer period of time your intensity MUST be decreased due to the mere fact of survival. 
If you decrease the amount of time you train(on whatever exercise,movement or skill set) your intensity can then- and should then- beincreased to the utmost to benefit.

Think about it.  Let's use sprinting for an example. 
If you sprint for 30s on the treadmill at an all out "balls to thewall" pace you will go hard. Let's increase the time to a 1 min.sprint. Think about that for a moment. Your pace- speed and intensity-will be lowered as compared to the 30s sprint in order to last the full1 min.

The same principle can and does hold true for any sport, weight training workout, and/or cardio(hopefully you perform HIIT).

Recovery proceeds growth.  Recovery proceeds growth. 
Less is more.  If you keep the intensity high you will not have to do as much in order to experience the same results. 

Some of you may only be into fat loss, but the following research also holds true for VO2 Max as well.

The landmark study in interval training was from Tremblay et al.Thisstudy directly compared 20 weeks of endurance training against 15weeks of interval training:

Energy cost of endurance training = 28661 calories.
Energy cost of interval training = 13614 calories (less than half)

The interval training group showed a 9 times greater loss insubcutaneous fat than the endurance group (when corrected for energycost).

Read that again. Calorie for calorie, the interval training group lostnine times more fat overall. Why? Maybe it's EPOC*, an upregulation offat burning enzyme activity. It doesn't really matter. I'm a real worldguy and if I can work harder, but for less time and see greaterresults- then I'm all in!

Every bodyis different; however certain principles of training and exercise doblanket all humans and all human's bodies. I have trained hundreds andhundreds of individuals over the years. What I've seen is that mosteveryone- unless there are certain sport specific endurancerequirements/goals- responds very well, and almost can say the best, toshort bouts of a given workout, exercise, movement, or pattern.

*EPOC (Exercise Post Oxygen Consumption) isdefined scientifically as the "recovery of metabolic rate back topre-exercise levels" and "can require several minutes for lightexercise and several hours for hard intervals."