It's not, but it's not a big deal to me either way.
If you put it all in one thread, the line move is even more noticeable and predictable. Some books are members here. They can subscribe to the thread just as easily. The semiorganized chaos we have with randomly posted picks in new threads allows a greater chance in the long run. You're not going to be able to get down much more easily if you receive instant notification via a subscribed thread, because EVERYONE will receive that notification.
If you have slow-moving sites that clone the big boys' lines, you'll be fine either way. That's why I don't really care much. My point is that no one should think posting in a single thread is going to be some sort of panacea. It mixes it up, but it doesn't really make it better, just different.