In particular, secure updates from itself so if all 4 nodes get hit simultaneously the deploy doesn't work. It deploys cleanly with --limit 1.
A separate change to the phage remote workflow in Instances exposes these options as flags:
- --limit: Run only this many commands simultaneously.
- --throttle: Wait this long between starting commands (for example, --throttle 0.25 will only start 4 commands per second).