Thanks Robin, how often?
Don’t know for sure.
Sit in front of the screen and watch.
If you have time right now we can make an experiment.
You sit still and watch while I update my posts in this topic and add timed posts
Edit:
SSGToms and I tried this and the posts appear instantaneously while one of us is watching the topic. No delays, no need to refresh et.c. 
Your posts are appearing instantly, as you hit reply, and there is a little “replying” icon with your avatar below the thread while you type. So there is no timed refresh rate, it’s all instantaneous.
mwahahahaha 
and discobot is envious that we seem to be “hitting it off”
"You’ve replied 3 times to @SSGToms in this particular topic!
A great discussion includes many voices and perspectives. Can you get anybody else involved?
And don’t forget, if you’d like to continue your conversation with this particular user at length outside of public view, send them a personal message."