I would say that before she left for the year, we would O-sync over half the time...
Generally speaking, simultaneous Os are *very* unusual. The simultaneous O is definitely one of those ideals about what a woman's O is "supposed to be like" promoted in both popular media and porn that I think very damaging. It is often portrayed as a sign of deeper intimacy or a sign of "true love" which actually puts pressure on the woman. Now not only is a woman supposed to O from IC alone, but at the same time as her P. Ack.
It is difficult if for no other reason that when a man is about to O he changes things, and changing things often causes a woman to at least temporarilly stop progressing toward O.
Best, Oldtimer
P.S. I'd like to again suggest that a woman is about as likely to be forthright about her faking habits as a man is about his porn habits.