It would be very convenient to have the option to create extra end pages. Now you can do this by creating an information page and set an extra rule on the page before that to make sure that records are set to completed if the respondent gets to that point in the questionnaire.
However, it would be easier if you could just add an end page with (at the background) the correct set-to-complete rule already applied.
Also, in the page settings, there is a redirect URL and redirect time which you can select for an end page but not for an information page. To have those options available for extra end pages would also be convenient for users.