The PDF Association is hard at work on a "PDF Structure Elements Best Practice Guide" to answer questions like this - an early draft is here http://www.pdfa.org/wp-content/uploads/2015/12/StructureElementsBestPracticeGuide_2016-01- 19.pdf
Until the final is published, my go-to place for PDF tagging best practices is the PDF/UA Reference Suite (PDF/UA Reference Suite | PDF Association )
Your TOC structure looks good to me - except I am not quite sure what the '1' is in your example. Like you, I artifact the dot leaders and see no added value in separating Chapter number and title.
a C student
I have the draft guide you noted and even in its rough state have found it very helpful. Thank you for pointing out the other location. I'd been on the website, but had missed that page. The example tagged files answered some of my other questions.
The "1" is the page number. Some guides I read noted that page numbers have no meaning in a world of reflowed text and others included the number. The PDF/UA Reference Suite example I downloaded has the page number.
If we give the reference tag jaws reader read the content 2 times. Do you face this issue
gansanban, As of now, I do not have the Jaws reader to test with.