Want to have my TOC call out a series of pages instead of individual pages

I've used a "brute force" method for this in the past.

Throughout the document, create and use three styles for each section

• SectionHead_Start
• SectionHead_Middle (other styles are based on this one)
• SectionHead_End

In the TOC, look for the Start and End styles in the documents. (It was a multi-chapter directory.)

Format them to two separate styles in the TOC.

TOC_SectHead_Start

TOC_SectHead_End (based on TOC start)

After the generation of the TOC, I would use a saved GREP query to look for the TOC_SectHead_End text through the tab and replace an En dash. Then replace the TOC_SectHead_Start paragraph return and replace with nothing. (I used a utility to automate the two searches.) 

The only downside is that I had to run the search after every TOC update, but it only took a few seconds.

Yes, I don't like using the index for a toc, but it can do page range options for you. See "Page Range Options in Indexes":

https://helpx.adobe.com/indesign/using/creating-index.html

That would be a neat trick in the ToC generator.

I used to use the following GREP query (coutesy of Peter Kahrel, I believe) to consolidate "Index to Advertiser" lisitings that were really a TOC in a directory:

Find: ^(.+ )([\d, ]+)\r\1([\d, ]+)$

Change: $1$2, $3

As I recall you need to run it until it finds no more matches.

The index panel can do that. You could then style it to look like a ToC.