We use Ceph for block and object workloads (no CephFS). Most of our clusters are still on Luminous (v12) and Filestore (XFS), and only our newer clusters that are being built now are on Nautilus (v14) Bluestore. We plan on migrating to Bluestore this year (and likely next year).
I'm on-call basically all the time, but we'll have maybe 1 issue per year where we have to act immediately. Most failures that would happen on a Saturday can wait until Monday to be acted on.
The smallest cluster that we'll build is 6 nodes. Our largest cluster now is 120 nodes with 1920 OSDs. We might build a larger cluster this year.
Back in Ceph Hammer days, I had a 6-node cluster lose 3 nodes, one node at a time, over a course of a couple of days with zero downtime.
We deploy with Ansible, and have our own, very paranoid and opinionated playbook for doing a rolling cluster reboot or restart, that checks multiple things before moving on to the next node.