Unless something has changed recently, the Intamin Free Falls used to have all the carriages released at the same time. When SFSTL installed the old AstroWorld ride they programmed the staggered drop sequence. That was the first time I ever saw a Free Fall not drop at the same time. I've ridden the ones at Kennywood, PGA, SFGAm, Canada's Wonderland, SFKK, AstroWorld, SFA, Elitch's, and SFSTL.
Here's a video of the one at Great America:
http://www.youtube.com/watch?v=udd8tcPXoA0
And here is Pitt Fall at Kennywood
http://www.youtube.com/watch?v=plOv011_oSY
Like I said, things may have changed, but I remember the cars dropping at the same time.