A chapter marker should help a listener move to a useful part of an episode. It does not need to mark every question or every change of speaker. Start with the main sections a listener might reasonably want to revisit.
Name the destination clearly
Use a short title that explains the subject. A title such as Setting up the first garden plot tells a listener more than Part 3. Avoid promising a conclusion the section does not actually contain.
Place the marker just before the relevant discussion begins, leaving enough context to understand the opening sentence. Starting halfway through an answer may save seconds while making the section harder to follow.
If the episode has an introduction, main interview and closing resources, those may be useful starting points. Add more chapters only when the content supports them.
Use the final audio as the clock
Structural edits change timing. After the final export, check every chapter against the listening file. Listen for the first words after each marker and confirm that the title matches the section.
The Podcasting 2.0 chapters format can link an external chapter file from a feed. That does not mean every application displays all chapter features. Use the current capabilities of the host and target players rather than promising a universal layout.
Open any linked chapter resource through its public path and check that it refers to the current episode. If a corrected audio file changes the structure, review the chapter times again. Keep the chapter source beside the project so later updates do not depend on someone reconstructing the timing from memory.