I'm pretty sure it's a constant shuffle.
Either way it's completely random. The only difference is situations where you fold and would of won you might not actually have won if you called. But that doesn't really matter and we shouldn't be thinking in that way anyways. Though it's hard not to. lol.
I know I shouldn't even think like that, and I would never let it affect my play either way. I'm just curious and I'm pretty sure there's nothing on the website about it.