Spring and Summer Training

There is a Chinese saying:  Open up to new practices in the Spring, avoid sweating in the Summer,  Develop Power in the Fall, and Store Qi in the Winter.
Why not practice everything all year round?  If gongfu/neijia(inner arts) is not a processional religious tradition why would we practice this way?  Is there any good reason?
Let’s talk about what the saying means first.

Spring:  Opening up to new practices, of course means learning new routines and new techniques, but it also means stretching more, increasing your range of motion, and breaking up any stagnation leftover from Winter.  Usually Spring is associated with the Liver organ, which "stagnates" from too much fried or greasy food.  The liver is "tonified" by vigorous movement.  Spring is a good time to sweat a little.

Summer:  Not sweating is a form of endurance training.  This season is associated with the heart, which is the Emporor of the Organs.  The country is well run when the Emporor has nothing to do.  Of course we know the heart is a pump that needs to keep pumping, but does it need to pump fast?  To understand how not sweating can be endurance training consider running 100 yards as fast as you can and timing it.  Immediately take your  pulse.  Now try to run the same distance in the same amount of time, and try to do it with a slower heart rate.
The Chinese idea works just the opposite, try to move as much as you can with out increasing your heart rate enough to break a sweat.  Over time you will be able to move faster and more vigorously without increasing your heart rate.
Running through a few Shaolin forms at performance speeds still gets me breathing hard.  It feels good, but I don’t do it everyday, and I actually think it would be counter productive if I did. When I go backpacking with a heavy pack, everyone else seems to get tired first, so it must be working.
I would argue that we really don’t need what many people call "cardio-conditioning." What do my 100 a day readers think?