The "let go of everything" method does not work on all aircraft. I seem to remember being told that this method is dependent on the A/B ratio (ratio of weight in the fuselage, to weight in the wings) of the aircraft as it effects the gyroscopics of the spin.
In terms of recovery training if you are taught to recognise the onset of a stall, and to fly the aircraft in balance you should never get into a spin (unintentionally).