When this option is checked, then a User will be able to Finalize a Calibration record that has been saved as "Incomplete"

If this option is Not checked then Users will not be able to Finalize Calibrations that have been saved as "Incomplete". There will not be any warnings or messages, however the Finalize checkbox on the 'Calibration Info' tab will be grayed out.

If the Calibration record has an Approval Policy associated, then the final signature checkbox will not be available.

If you are not going to let Users Finalize Incomplete calibrations, it would be a good idea to set the Reminder, on the Group screen, Reminders tab for "Show Incomplete Calibrations".