yes right, I have seen it too, but they did not send the invitation already, I guess. Hope they are going to do it this week, and perhaps propose some other dates in november.
8 hours is indeed really long, but it may just be the longest it can take. Let's say, it starts at 7:45, then 8 hours later the last candidate of the day end his personal interview, meaning we can finish before that.
So do not expect to wait that long except if you are unlucky enough to be the last one doing your interview.