Say you scaled up to 100 nodes for the holiday season, is there any way to tell how many/much storage/nodes you have to keep running in order to keep 3 backups and maintain your new post holiday load?
By just looking at your max load over the last 24h or perhaps week, it would be pretty easy to see when to down scale.
That being said, as long as you remove the cockroach nodes one at a time , it's pretty easy to down scale a cockroach cluster.