1. when we say go, we go for 30 minutes
2. at 30 minutes we stop to compare word counts and notes on how things developed.
3. Then we go again.
During sessions chatting is mildly discouraged, though telling a latecomer when the present session is ending is all right. We don't usually do coordinated prompts as too many people have things they want to work on, but if you want a prompt, I'm sure we'll be able to come up with something.