There are many types of stretching... I believe isometric stretching is when you reach a certain point and hold it there, meaning that you probably are not applying a constant amount of force because you have chosen a point to stop. Dynamic stretching is movement stretching, butt kicks, walking straight leg raises, etc.
Now, the degree to which stretching will improve certain attributes is debatable. It totally depends on your goals. If you are a power type of athlete you probably do not want to stretch too much. You may get to the point of slight plastic deformation, which means you have stretched the muscle to the point where they will not return to their original length.
If your goal is to become very flexible for some reason then stretch is fine, and for bodybuilding it can have some practical applications because it has been found in some animals that prolonged stretching can increase cross-sectional area. This was done with 24 hour per day stretching done to dogs, and power and strength were not tested afterward. But it is important to know that stretching is electrically silent until the end range of motion is neared and stress is placed on the muscle fibers.
I have to go or I would write more but, I definitely stretching is overused and it maybe has more mental value than physical...