I think it depends on the operator, the ride, and how many times they've seen you on that ride recently. I've gotten plenty of re-rides at Six Flags parks, and they've come over the PA and said "You may stay on if there's no one in line for your row." But sometimes they make you exit and come back through the queues, most likely to reduce the cumulative effects of G-forces. I rode the Shockwave at SFOT 6 times in a row once, exiting and re-entering through the queues each time, even though there was no line, and on the 6th ride, I blacked out in the loops. I was lucky they even let me ride it again, because after the 5th ride they were looking at me like they were concerned for some reason, no doubt because they knew that I'd be blacking out soon, if I kept on riding it so many times in such quick succession. Anyway, blacking out was cool, but it was pretty scary, because that had never happened to me before, and I didn't try to push my luck any further by getting in line again after that. I was certain that they wouldn't let me ride it anymore after that anyway, just by the way that they were looking at me before the ride that made me black out. It's amazing how attentive most ride ops are. It may seem like they hardly even notice you sometimes, but they're usually more aware of what's going on than you are! I'm glad that I got to black out though, just so I know what it's like, but I don't really want to black out on a ride again. It's too disorienting, and I imagine that it might be a possible cause of some of those notorius "brain bleeds" that we're hearing so much about these days, in some cases.
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