automate table of contents updates when new pages are added?

Not without scripting or a third party plug-in. There is a plug-in offered by ID-Extras called LiveTOC that may interest you: https://www.id-extras.com/products/livetoc/ - it is a paid plug-in.

Hi @jerryjohn2 , Do you need more than Layout>Update Table of Contents with a key command assigned? A script could listen for some kind of event and automate the update, but that might come with some unexpected or unintended updates.

JerryJohn,

When you make a ToC, also name and save a Style name, like "JJsToC". 

But after editing changes, you have to click on Update Table of Contents. It does not run itself.

Have you considered making a checklist of things to do to a finalizing publication like update ToC, Index, and running the spell-checker?  Visually examine each page? These are still careful human endeavors.

Might be scriptable, but otherwise nothing I'm aware of.