ITs true ,its a slow art that helps with all other parts of your training,its stop you getting damage from fireing up too soon from a cold start, and I think it helps with fluidity and therefore speed in techniques.
But you can do damage and go backwards very easily though and like Scrap said you are tearing , stretching and repairing even in small doses, but thats the idea (so that when you do go flat out you've already done the work through those zones so it doesnt create a big tears or worse in tendons. Just dont go over board to fast or into a low painful stretch to soon.

You can do shoulders,waist neck,back every muscle and tendon area you have.