Ethereal

It generally isn't so important in OPs. Because of the rate at which OPs move, people generally just try to get as many posts in as possible. You never know when the thread's creator will close it. People also come and go in OPs so often that you may be waiting on someone who doesn't feel obligated to post again. It would probably be a good idea for the thread's creator to make a note about post order in the first post if that's something that they'd like to see.

That makes a lot of sense, thanks :)