What are you assuming about exposure? If a SSH key lives on a well-secured workstation or bastion host (and you ideally don't agent-forward it to insecure hosts), rotating that key once per hour doesn't seem a top priority to me? E.g. a sudo password is (lower-impact, but) more likely to get exposed to compromised hosts?
("Well-secured workstation" is arguably an oxymoron, of course...)
