[KevinH]

There are many kinds of Tables of Contents (TOCs) and that makes things confusing.

There are:

1. html TOCs that you completely control and are meant to be seen by the reader just like any other chapter. They are not used to generate any internal navigation in the e-reader.

2. epub2 has an xml based TOC typically called the toc.ncx that is meant to be machine read by the e-reader and used to build an internal TOC for navigation.

3. epub3 removes the need for the toc.ncx (but you can add it back for compatibility with older epub2 only e-readers). It instead adds the nav.xhtml and it is machine read by the e-reader to build internal TOC for navigation. But if you add the nav.xhtml to the OPF spine fo the book, it can double as an html TOC as well.

So you control which type of TOC you want, and if you want to add an html TOC or not.

As for kindles, I really have no idea as I gave up on kindles a long time ago. It is not an open standard.

Perhaps someone that produces ebooks for Kindles can tell you which is the best way to create a TOC for a kindle.

As for Apple Books, epub3 with the nav.xhtml properly specified in the OPF should create the Apple Books internal TOC, and if you add it to the OPF spine it should also appear as an html TOC. There is no reason to create a second HTML TOC for Apple Books.