All of the above.
I've worked with companies in highly regulated industries, and they need to be able to tell an auditor that anyone who completed a course was exposed to all of the content. That, of course, doesn't actually mean the person read it or understood it. But that's how compliance works...
The other debate is whether to change NEXT to Hidden or to Disabled.
- I disable it. Why? Because, when it's hidden, the PREV button moves into its place, which can be distracting and/or frustrating (e.g., if one clicks there expecting it to go next...). But I recognize that this is a matter of preference.