We transfer ACH files(i.e. paychecks) via SSH(SFTP) to several banks. You better believe I check keys. One of the banks forces key rotation every 2-ish years. I absolutely verify it every rotation and delete the old keys.
Occasionally it fails, almost always it's something unexpected happening, but occasionally we catch their errors(verified by connecting from various endpoints/DNS queries/etc). We used to call them all the time whenever that happened. Now we just auto-retry on failure in an hour and that fixes the issue all of the time(so far). We only re-try once and then fail with a ticket. Most of us like our paychecks, so we are pretty good about getting that ticket resolved quickly.
Occasionally it fails, almost always it's something unexpected happening, but occasionally we catch their errors(verified by connecting from various endpoints/DNS queries/etc). We used to call them all the time whenever that happened. Now we just auto-retry on failure in an hour and that fixes the issue all of the time(so far). We only re-try once and then fail with a ticket. Most of us like our paychecks, so we are pretty good about getting that ticket resolved quickly.