Asking for feedback during timed test
At my company, we're building an online test-taking experience, and we ran into a problem. We would like to find a way to encourage our users to provide feedback during the test; however, since tests are timed, users are clearly uninterested in wasting time providing feedback. Here are the solutions we thought of, with the respective considerations we made.
Adding 30 seconds to the timer whenever a user submits some feedback → We're going to get a lot of "hdkjgnhgkdndj" feedback from users who need more time
Showing an interstitial "Provide feedback" screen after submitting each question (freezing the timer) → This is a clearly intrusive solution that would worsen the test-taking experience
Showing two distinct "Submit"/"Submit and provide feedback" buttons to let users choose whether they want to provide feedback for each question (and freezing the timer while they're providing the feedback) → Two "Submit" buttons would clutter the UI, especially on mobile devices with smaller screens
How should we approach this? Are there any best practices we should keep in mind? Should we just A/B test solutions until we get the most feedback?