HI All,
It is so true that the cord should be left to cease pulsating until severance. Their is at least one exception I don't think has been mentioned yet however and that is during a waterbirth. The ambient temp approx 37 celsius delays cord ceasation and we used to severe after a reasonable time a min or two.
Another consideration is the babies position in relation to the placenta to assist or inhibit bloodflow too and from baby (important when considering Bilirubin breakdown etc later on.

Blessings to all

Nigel