I use a different keypair for every service, and for each device connecting to the service because keys are cheap and easy to manage. One advantage is that if o

I use a different keypair for every service, and for each device connecting to the service because keys are cheap and easy to manage. One advantage is that if one or more private keys is compromised or potentially compromised, you don't need to revoke and reissue all keys. Another, possibly more practical advantage is that I prefer to have a per-service persona that is not tied to other services. Shared public keys makes it easier to link together different accounts as belonging to the same person.