You don't need an HTML ToC in ePub as ePub 2 as NCX and ePub 3 has NAV which is easier to get to from any place in the eBook. I have seen some ePub with no HTML ToC.
If you are making an ePub 3, you do also need the NCX for ePub 2 compatibility.
Personally, I don't use the HTML ToC if there is one. I use the ToC that's displayed when I want to see the ToC and that is not the HTML ToC.
|