Re: Spill over
I am convinced my body understood something by continuously trying to adjust against the subtle attempts of my teacher to take my centre (by which he personally means something that occurs before visible movement). So my body had a some idea of "ground paths" and even an inkling of "stupid jin" before I once went to a seminar with Mike Sigman from whom I take that terminology.
OTOH, much like Jason I do not think its very efficient at all to practice that way, and I do not think it will lead to an "IS body". Well, maybe unless you are amazingly talented.