Yes, this is very common. Indeed if used as a fileserver and by many users it is absolutely essential. SFTP uses SSH, and there is a lot of EDI activity that depends on it too.
From devices it is possible to trigger events with custom user logons (such as poweroff or reboot).
Consider also SCP (WinSCP is commonly used to access source code), and KDE users still able to use fish: in Konqueror.
Notable too is the use of additional ports in case of loss during maintenance (Ubuntu do-release-upgrade, say).
So yes, I gather you have never had multiple PuTTY terminals open ?