I am by no means experienced in this arcane magic but from the little I have discovered; the quantity of NaOH used makes a big difference to the time it takes to break emulsions.
I usually shake for 5 mins with warm naphtha, let to settle which takes no more than 10 mins and repeat 3 or 4 times. On the last shake I then let it settle completely for up to an hour.
Sometimes the layer looks very clean after a few minutes. If you pull right there you will often find that a new layer of NPS has separated even further by the next day.
I don't know much, but I do know this. With a golden heart comes a rebel fist.