I have been lucky enough to have multiples several times, in randow times. Not sure what the menu was that caused it, but it was amazing. Those and the ocassional 30 minutes of pure innercouse keep her smiling. If I ever find a common twine that causes it, I will update here.
For now, it is a crap shoot....but she keeps coming back to see if she gets lucky.
p.s. Yes, se has asked me to stop before, when a session kept going, and her orgasms were done and she was finished. Now I kinda know how she feels at times.