If nothing was unclear or difficult, say so. Skip questions about steps you did not experience; use not applicable where appropriate.

Which scheduling instruction was unclear?
What arrangement would make participation easier?
What preparation information was missing?

Author notes / illustrative keys where applicable:
1. Use this answer to locate the part of the experience that needs explanation. The example issue to investigate is: participants cannot tell how long the session will last.
2. Preferred arrangements identify practical barriers involving timing, format or preparation for a voluntary interview. Explain actual available choices and keep participation optional, without collecting unnecessary personal circumstances or assuming stated availability guarantees attendance.
3. Turn the requested improvement into a testable next step. One illustrative action is: show duration and preparation details before booking.