Hi @daveburton, and thanks for your query. Yes indeed a unique calibration is necessary for each new user as the algorithms in place depend very much on the uniqueness of the human eye from person to person.
However, within the Tobii Core Interaction Software running in the system tray, you can save and load user profiles easily so that one once an initial calibration is performed, you would only need to switch profiles thereafter.
Additionally, should each user have their own login and have created their own Tobii profile, then this profile will be loaded upon login.
Hopefully this answers your query, but please let us know if we can provide any additional information.